"This is the Nissan Primera GT, as raced in the 1999 British Touring Car Championship (BTCC). The Primera is powered a 4 cylinder 16 valves 2 litre engine that produces over 300 bhp @ 8300 rpm."
And if anyone mentions 1916cc's I will delete the comment... Straight away :P
[Edited on 8-4-2004 by Cam]
56astro ·
aluminium case
de-stroke it
twin overhead cams
variable timing
ceramic internals
fuel injected
Cam ·
I don't think variable timing would work. They remove them on race cars anyway, too much reciprocating weight. Plus you gear your car for a specific powerbands. I think light valve train is the go. I know V8 supercars are pushrod operated, no ideas what the specifics are tho. But they pump out over 620BHP.
Ceramic internals... What do you mean by that? I know you can get ceramic valve gear, but never heard of ceramic internals before.
modulus ·
Just munching it over casually, 150 bhp per litre is quite high, and probably beyond what could remotely be called "streetable" .
Some streetable bikes produce specific power outputs of this order, but the power/weight ratio of these bikes is such that "streetable" ceases to be an issue; what I mean is when you have over 150 bhp for only half a tonne of bike, you'll find a way to get it through the traffic without stalling; this means that cam profiles can be quite radical.
To get into the range of 150 bhp/litre on pump petrol (not specified, but a major limitation assumed), normally aspirated, the engine would need every advantage known to engine building; the best n.a. Chev 383's don't come near 940 bhp on pump fuel, largely because of the valve train.
The engine would need to be water-cooled (air-cooled might do for dragging, not for continuous output in this range), have overhead valve gear and multi-valve heads; it wouldn't really resemble a Type 1 engine.
The other critical element right from the outset is the combination of bore/stroke ratio and con-rod angle; I think you'll find that you'd be having a careful look at why certain Type 1 engines of around the 1.916 litre capacity (not to put too fine a point on it) deliver very good horsepower, considering their otherwise antiquated design (valves and valve actuation).
Overall, I can't imagine why anyone would bother, or alternately, having bothered and achieved something like 150 bhp/litre, what would have been proven. Still, fills in an evening.
Thats turboed dude 😉 Love that car though. Going to see it in the flesh in a couple of months. :bounce
It can be done, I'm sure it can. Pneumatic valves would be a must have! And fully custom built light weight valve gear too. As I said... V8 supercars can get 620+ on shell optimax, so it must be reachable. There are big cc Type 1's in the US running on pump gas with 250.
BTW, this would be a race only engine too guys 🙂
Kai.A. ·
why limit yourself by not using a turbo though?
i'm assuming you have a reason you wanna go n/a....
kai
modulus ·
Cam wrote:... V8 supercars can get 620+ on shell optimax, so it must be reachable.
Errr...that's about 108 bhp/litre.....
Cam wrote:there are big cc Type 1's in the US running on pump gas with 250.
I thought by "the same hp" you were implying in some way comparable with the Nissan 2 litre... there are 600 c.i. engines also turning out big numbers, but not 150 bhp/litre....
Cam ·
No reason. Just thought it would be a good thing to think about. However I do like the responsive nature of NA engines over artificial. But thats a whole other argument that we won't get into. I do however know that WRC cars are limited to 300 BHP so use the turbo's to get as much torque as possible over 600NM's. Which is a turbo motor I like the sound of 😀
Cam ·
Errr...that's about 108 bhp/litre.....
I thought by "the same hp" you were implying in some way comparable with the Nissan 2 litre... there are 600 c.i. engines also turning out big numbers, but not 150 bhp/litre....
Yes, yes, I was. Just thought it would be an interesting topic of conversation.
I know a guy in Sweden who put 911 heads on a type 1 motor about 30 years ago, stainless steel plates either side of the magnesium case with big through bolts. This would be a must do head conversion for a big HP AC motor. twin plugs, OHC's, better cooling, etc...
As I said, just interested to know what you guys think and how you personally would attack the task.
low55 ·
cam about 5 years ago my uncle had a moto in his race buggie that was good for about 200 it was a type 1 engine it was werth a mint and it was fast it won its class the fist race and blew up ever race after that it was n/a but i imagen tecnoligy has gone a long way in 5 years and he now runs a nissen motor in near standed trim with tons of boost and its so much more reliable and is it fast
Cam ·
oooh, nice 😀
I'm gonna give you a call this coming week dude. We'll have to hang out 😎
Kai.A. ·
i agree that the 911 head conversion is definately a good step forward, that's why i like russ's bug so much, the turbo just gives it that extra bit....
there was a bug a few years back that competed in autocross in the uk, i can't remember if it was t1 or t4 based, but it had subaru quad cam heads (the heads were water cooled, the rest of the motor was still air cooled....and a turbo too
this thing pumped out around 500bhp i think!:P
kai
low55 ·
yer a lots happend since we last chated you would not beleve the things that have happend to me over the past 2 months
Cam ·
Yep, I know the one you mean, Kai. Belong to Pete (surname escapes me). He passed away a couple of years ago. Apparently his brother has the car and has put the word out that it is for sale.
Travis, yeah man. You said you had a stack on the phone. Thats shit man. I'll give you a call on tues or something. Or give me a call on the weekend if you want to catch up.
1303Steve ·
Hi
Comparing apples with apples, a 2 litre Kombi motor puts out about 60-70 hp, a 2 litre Volvo motor (still with pushrods) puts out around 120, it must be in the heads, cam etc.
On the other hand no one can get near Gummleys supercharged type 4 powered hillclimb car, even when using twin cams, 16 valves, turbos etc.
1302Steve
Cam ·
Yeah, Gummley's is nuts!!! Just shows how much aircooled motors love methanol 😎
Kai.A. ·
how bout some more info on gummley's please....
kai😎
empi man ·
And who are you to play God when someone mentions 43.772137 squared!!!!The truth hurts!!!
OvalGlen ·
Last Sunday , I spoke to the guy that did heads on Gummleys ...
I'll be sitting with him on Sat at Drags.
He told me some techniques but best to ask him
yourself, introduce yourself at drags.
AdrianH ·
There are 4 valve per cylinder heads available in the US...
As for 300 hp, I know of a couple of midgets running T4 based engines and methanol making 320ish Hp, but they are more like 3l.
[Edited on 8-4-2004 by AdrianH]
56astro ·
Cam wrote:However I do like the responsive nature of NA engines over artificial.
I thought some super chargers has power-on-tap, unlike turbos with their infamous lag.
There was an interesting article in a recent Motor magazine comparing a commodore and falcon, both with s/c. Different types though. The commodore had grunt from go to whoa! While the falcon had it from about 2500-3000rpm.
Craig Torrens ·
I would be looking at motor bike engine technology/principals, they seem to have one of the highest HP per cc.
AdrianH ·
Superchargers are parasitic, they suck HP to make more, turbos if sized properly dont display the lag of days gone by, 300 hp out of a T1 is definitely possible, then just turn down the boost for the street.
tassupervee ·
150 BHP/Litre is well exceeded by most large production sports bikes now. However, this is done with obscene RPM's Always in excess of 10,000rpm.
Crikey that would be one bit of work to get a kraut to rev like that...at least once anyway!!
A way of attacking this would be to look closely at adapting the heads off something like a big inch Ducati or similar twin which will have the potential to flow that much quite easily but to get the rest of a 'dub boxer engine to stay together at the revs demanded may well be an exercise in futility!!
Bwaaahahahah imagine that ratty old beetle whizzing away down the road at 12,000rpm!!!!!!!!
Craig Torrens ·
use the new aluminum cases.............................destroke the crank like Ducati has done.............................maybe a turbo (although we want normally aspirated!)............mmmmmmmmm imagine a 10000rpm beetle:thumb
sweeeeeeet.
Anthiron ·
i can imagine the engine blowing apart..............
tassupervee ·
You are imagining correctly dude!!!!LOL
AdrianH ·
Desmodronic valves ??
Kai.A. ·
vw flat 4 motors will never be high revving motors!!!! apart from very occasional crazy drag race combos, like 1584cc 13 sec. (i think) drag car in the u.k a few years back, that revved to 9 grand!!!! 48 ida's on a 1600.....
that's why i reckon a turbo is the way forward, you can set it up so that full boost arrives nice and early in the rev range, maybe 5000-6000rpm.... that way ya don't have to screw the nuts off it for the power.
then there's always the NOS bottle..... and water injection..... there's tonnes of stuff you could do.
kai😎
Kai.A. ·
the yellow cabrio
puts out around 220bhp (i think) n/a and then has another 100-150bhp of NOS on tap if needed.....
kai😎
[Edited on 9-4-2004 by Kai.A.]
vw54 ·
1 Have a LOT of Money
2 Have a lot of time
3 30Lbs of Turbo Boost
4 Run it on Methonal
Craig Torrens ·
Kai.A. wrote:vw flat 4 motors will never be high revving motors!!!! kai😎
Never say never.😉 plenty of VW's producing the revs. Peter Gumleys supercharged T4 revs past 8000rpm no probs.
to produce that type of HP (300hp) from a normally aspirated 4cyl you will always need high revs. That's why the Nissan is producing the power at over 8000rpm.
If only VW's had another two bearings holding the crank !!
Kai.A. ·
yeh. 8000 is probably around about the limit for a race motor.
we'll never get 10,000 plus like motorbikes though....
and if reliability is an issue then it'll definately never reach those kind of revs....
if you read some of the power outputs the americans are getting, often from 'claimed' street driven cars, you've gotta wonder really, 300hp isn't too extreme for them....
kai
Craig Torrens ·
do Americans have 300hp with normally aspirated motors ?
I'm not up with American cars, so are they claiming these figures?
how are they doing it ?:jesus
there's your answer Cam !
Kai.A. ·
probably not 300hp n/a... it's just every time i see a mag or website with american dubs their power figures seem huge!
i'm gonna scrounge round my room for some magazines.....get some actual figures up here.
kai😎
Craig Torrens ·
I had a look at that Russ Fellows drag car from your suggested web site................he is only doing 14.01 without the turbo:jesus......................we have plenty of normally aspirated cars in the 13's !
11.2 with the turbo !!
Amazing how a turbo can make up for performance.
Kai.A. ·
just found an issue of ultra vw with a dyno day feature in the back....
the best n/a is a 2332 with 200hp, 177lb ft torque....
the best turbo is a 2332 with 336hp and 392 lb ft.
theres also:
n/a 1776 wth 146hp
n/a 2175 wth 185hp and 156 lb ft
n/a 2276 with 155hp and 144lb ft
turbo 2332 330hp 290lb ft
turbo 2276 332hp 330lb ft (in a bloody street driven buggy!!!!!)
turbo 2165 298hp 287lb ft
turbo 1914 266hp 245lb ft
so for an 'easy' 300hp, turbo is surely the way....
quite a few of them claim to be driven on the street too.
kai😎
Kai.A. ·
Craig Torrens wrote:I had a look at that Russ Fellows drag car from your suggested web site................he is only doing 14.01 without the turbo:jesus......................we have plenty of normally aspirated cars in the 13's !
i don't know the details of his run/runs without the turbo, but it's simple really, the engine is built for turbo, it runs cam profiles best suited for a turbo and low compression.
so it's not surprising that without the turbo it doesn't run that strong.
kai
Craig Torrens ·
valid point.
so 71mmstrokex104mm pistons...... and a turbo!
but Cam wants it normally aspirated !!!
Kai.A. ·
yeh, i know cam wants it normally aspirated.... the best example i have found so far is the yellow cabrio, but then he uses NOS to get the power.....
i spose really i'm putting forward my view that if you want big power you shouldn't overlook turbos, it's fairly proven that you can get huge power and reliability on pump fuel...
kai
Craig Torrens ·
no question about turbo's........ I'd love to have one !
but the trick here is to try and screw every HP without one.😉
tassupervee ·
Then there is buckleys of getting those figures out of a kraut without blowing it. Other than in our dreams......................
L8tr
E
[Edited on 9/4/04 by tassupervee]
Craig Torrens ·
there's your answer Cam.:cry
Kai.A. ·
with enough $ and a load of r&d anything is possible.
maybe a big type 4, like 2.8 odd.... then your only asking 100hp/tonne....could be more of a possibility.
kai😎
tassupervee ·
Ahh yes but he was quite specific in using type 1 clobber!
Fact remains is that to get 150BHP/litre is close to unnatainable with anything we can get our grubby little hands on and furthermore, I doubt iffen I could get that much from a dak dak id be buggered if I would let anyone in on the secret!!!!!!!!!
However, every man has his price................
:thumb
L8tr
E
whatnow ·
a few ideas i have been toying with..... bore and stroke ??? 69 or smaller stroke prob.
al case, through bolted. crank... make it with larger main and rod journals, poss narrow the rod journals and widen the mains... all to try and reduce crank flex.
94mm+ p & c. move the studs if necessary.
some form of overhead springless valve accuation, possibly set up to advance/retard the valve timing (not only crank angle timing but comparitive inlet and exhaust timing) to keep the thing on the boil.
a serious redesign of the heads... 2,3,4,5 valves??? twin plugs for monster compression. ports designed to reduce reverse flow so you can stretch the duration. designed by someone who can get the charge in and out and get the most out of it along the way. ie a top end race motor head designer.
if you want to stretch the power band... a system that will change the legnth of the intake and exhaust manifolds.
make as much as possible out of super expensive alloys. (bragging rights)
use every heat/surface treatment you can think of
find the most skilled and anal retentive balancer (and machinest etc too) in the world to work on it.
etc etc.
now who wants to throw say $20 or 30 million my way, i know i can do it (or at least find the people who can). anyone?
[Edited on 10-4-2004 by whatnow]
Cam ·
Wow! :o you guys are guns!!!
What are Desmodronic valves?
Ultimately that big HP in a beetle motor IS unrealistic. I can see it happening. But it would take US VWDRC team budgets and research to achieve it.
I do want snap on power though. Guess I've been out of fast dubs for too many years now 🙁
However... We have the weight advantage. But, I still think boost is the answer.
I like the idea of having it type 1 based. They're just LIGHT motors... And lets face it the less weight out back the better.
911 head conversion will be a must! As will 911 nikies. Blueprinting the induction so as the turbo is working as little as possible to make to most boost is also a must.
The bottom line... I dunno, it's good friday. I'm dog tired and unsure enough of my digestive system (chocolate aftermath) at the moment let alone where I'd like to go with an engine.
But I think this makes a great topic of conversation 😀
For some reason I don't think bearing strength would be much of an issue. But yeah, boost is the answer for our little four bangers!
Happy Easter All!
Cam
whatnow ·
cam, the stuff about increasing the bearing size is to increase the overlap of the journals and the meat in the journals.... to help increase the stregnth and reduce the flex in the crank.... ie to reduce the amount of hp lost and increase engine/case life. if you narrowed the rod journals and didn't widen the mains you could increase the web thickness... more strength.
desmo is a system that ducati used (in the 70's?), that uses a system of cams and levers to open AND CLOSE the valves. they origonally came with helper springs to help close the valves, but i think it was a common thing to remove them. ie while there was in increase in reciprocating weight, the engines weren't working against heavy springs to open the valves and they couldn't bounce (well noone told me they couldn't bounce but to me it is logical that they couldn't... unless you broke something 🙂 ). a quick search should find you more info.
right. it's nationals time.
happy easter all.
tassupervee ·
Youre pretty close with the desmodromic thing.
Altho desmodromic (desmo for short) is exclusively used on Ducati bikes, the design has been around since Adam was a boy, gawd only knows when and was in use im pretty sure well before ww2.
The system is not really that tech actually (other than from a design viewpoint) with the camshaft having 2 lobes per valve per cylinder which are mirror images of each other and a typical rocker opening the valve with another rocker working on its own rocker shaft mounted below the opening rocker shaft that works off the "other lobe" that closes the valve.
Valve clearences are set by opening "shims" (lash caps) and different thicknesses of the closing shims.
The valve itself has ordinary grooves machine into it and the groove located the collets that retain the closing shim, like an ordinary machined down spring retainer 'cept upside down. The closing rocker looks like a fork on the valve end and operates on the underside of the closing "shim".
Yes, there is a "hairspring" around the closing rocker shaft but the benifits of removing it in all but the most wild of race engines is pretty doubtful, you can push the closing rocker down against the "spring" with your little finger.
Benefits of desmo gear is little rotational resistance due to no springs and the valves are positively closed and cannot ever bounce.
Disadvantages are mostly from a design viewpoint, particularly in getting the included valve angles necessary to make a decent head work to actually be able to exploit the rpm ranges that desmo actuation will benefit and fitting in extra valves, its a nightmare from that standpoint.
I think a fundamental drama with getting the type of zing necessary here is that an oldefashioned crakcases are just a bit too flexible. I dont think that Ferdinand had 10,000 + RPM in mind when pencilling in the Peoples Wagon engine!
This is enough of a hassle with blown low rev krauts now. With the cases stretching all over the show!.
There are quite a few F1 engine builders tackling this very type of thing as we speak!!!!!!LOL
L8tr Men
E
AdrianH ·
If you destroked it to say 64mm, used a b piston or even a piston with a higher pin height (into the oil control ring) you would significantly reduce the width of the engine, could probably even run a slightly shorter rod.
This would help reduce the length (and weight) of the pushrods.
Changing the oiling system to the heads so it fed and drained without running through the pushrod would help.
The 6mm stem valves available and lightweight lifters allow use of single springs to 8500 RPM.
The case is the limiting factor, aftermarket cases with through bolts at the mains are a good start (performance technology, scat, new CB case ???)
One of the highest HP I have heard of in a T1 case is 260 NA, the car ran 10.60 in the 1/4, Geoff Hart racing in the US. I am pretty sure it was a 2332 running 62mm terminator carbs, drags only though.
If you want that HP on the track and still have it streetable then turbo is the easiest answer. Crank up the boost, pour in the race gas and your off !!
pete wood ·
spoke to the owner of the grey C&V drag beetle on easter saturday. While the car the was tyre spinning across it's lane it was over running into the 10,500-11,000rpm bracket.😠
Really serious stuff.
He's running a big dollar Pauter engine with draw through 4barrel holley/turbo setup. This means he can't run a rev limiter. He's already learn't that lesson. Blew up a plennum on the start line because of pooling fuel and nitrous while the rev limiter was working.
He said he doesn't know how much power the car is producing exactly as they can't strap it to the dyno well enough, it comes on boost and frys the tyres ON THE DYNO!.
He reckons it's producing around the 500hp (at the crank) mark with low boost and no Nitrous.
Without a turbo that might be the sort of power and revs your talking about, but I reckon it's bigger than 2332 and the engine would have to be worth in excess of $50k.
BIG dollars :o
Just a thought, why not cut some toyota 20valve heads in half and fab up some stuff to fit them to a boxer. With the destroking and big revs it might come close. Ferrari have been producing powerful, hi-revving boxers for decades, haven't they? 😉
tassupervee ·
Indde Ferrari have but not 150 BHP/Litre easily.
mebbe at F1 level.
Still the original post specified Type 1 clobber with no forced induction.
A very big ask!!!!
L8tr
E
pete wood ·
did any of you guys see a report on a slip-yoke (I think that was the name for it) set up for subaru boxers designed here in australia.
It had a single conrod (joined in the middle) going across the motor that connected with a piston at each end. The crank only had two rod journals. One for each conrod. The crank went in the middle and it had a slip bearing in the middle that was 0 shaped so the rod only moved laterally, not in a circular motion. This cuts down on side loads or something to make the engine smoother and revs more comfortably. Spose you could make one for an aircooled engine. However you would need a special crank and it would change the firing order. Does anyone know if onyone has used this setup before?
If it has been used before on say a BMW bike, you could steel the conrods from that and make up a crank to suit. It would also give you more room inside the case to add extra length for the case bearing journals.
What do you reckon?
Just another idea. 🙂
Che Castro ·
I think that another limiting factor is the essential design of the case. There are only 3 main bearings that support the crank with the 4th for the pulley. A EJ20T has a bearing between each journal which is much stronger which stops the crankshaft from flexing. in the type 1 case the studs are only threaded into soft magnesium, the type 4, porsche and scooby have through bolts which make much more sense.
Also the heads are pretty limiting, unless you manage to fit heads from another car on. The wedge combustion chamber design works on squish, the spark plug position is at an angle to the side. A modern head has 4 valves, pentroof chamber with teh sparkplug in the dead centre at the top. The chamber is designed for swirl, have u seen the Alfa Romeo JTS system? It utilises direct injection into the cylinder.
I dont think that a streetable and durable 300HP is likely from a N/A type 1 motor which uses at least a factory case - short of a small fortune pumped into the motor.
I am not criticising the design of the type 1, it was advanced for its time - but you would be kidding yourself if you are putting it on the same level as a modern motor such as the EJ20T.
I do dream of building a turbo 1916 or 2110 or something similar though 🙂 Shoehorning in a EJ20T would be too easy 🙂
GL1972 ·
What ever happened to the SPG Roller Cranks? Difficult setup with oil sprayers and all but they could rev! A guy I knew in the early eighties had a Manx with a 2180, 48IDAs with one. The thing would wheelstand easy.
AdrianH ·
The roller cranks are pressed together, under shock loads (like your friend was doing) they have a tendancy to twist out of alignment.
dozerman ·
It's all research and development.The old AUTOCAVEN rally cross beetle had a 2.1 t1 subaru 16valve head conversion and turbo I think it was making 500bhp.I hung out with some guys in texas who did chevys and the research they put into the old 2 valve pushrod motor was just amazingIn 1992 we dynoed a 403 cui splayed valve chevy with carburators on race gas made 980hp@ about 9800rpm if I rember correctly(this was the boss's engine.Another engine the same specs less 2 little tricks only made 910hp.So dyno time is where its at or using proven parts and info.P.S. In the NHRA PROSTOCK class the development costs for 1 hp are $100,000 U.S.
dozerman ·
it's all about research and devolpment and the physical limits of your particular mechanical combo.There is a formula that can give you max hp of a particular engine I can't recall exactly but it's got to do with valve area vs pistion area it's a pretty complex deal but they use it for F1.All engines are air pumps so a lot of tricks will transfer across to the vw engine,not all will work thats why they call it R+D.As for the small block chevy I hung out with some real texans that ran a pair of B/Altereds(oldsmobile cutlas) in 1992 (very simular to our pro stockers)402cui splayed valve heads dominators vpc18 fuel yada yada it made 980hp @9600rpm (723@178ph) another identical engine with a normal firing order and angled intake(conventional) made 70 hp less.They say in prostock in the USA it will cost you $100.000 U.S for 1 HP.I say keep your eyes open and look every where for secrets because if guys with 1400hp engines are looking for 1-2 hp they will try anything it might take a while but the numbers soon add up after all it's only money right.haha
pete wood ·
what if you got a 1litre vw motor to produce 150BHP first?
it would be a good staring place.😉
Che Castro ·
it was only the SPG roller cranks that were pressed together without any locking system. I think other roller cranks like porsche ones locked to the rod journals with a spline. The SPG ones often twisted out of true from drag race starts. Also the SPG ones would be stuck with the same set of rods it's entire life. Research has also shown that plain bearings have less drag and longer life than roller bearings in a crankshaft application
amazer ·
1302Steve wrote:On the other hand no one can get near Gummleys supercharged type 4 powered hillclimb car, even when using twin cams, 16 valves, turbos etc.
1302Steve
Gumley got beaten a few weeks ago at the Victorian Championships. By an imported Pilbeam with an engine that I believe was handmade from scratch, I think I heard the figure $30,000 mentioned. I dont know what the times were, but I know they were close, the pilbeam was on new tyres, the SCV on old tyres and Pete was getting closer each run. Pretty good that a car built in a shed in wollongong can come close.
I dont think that 4 valves is the way to go. Not from any scientific engineering analysis, only by driving japanese cars. They have absolutely no pull at low RPM. You have to rev them to get them to go, and the VW case doesnt really like to have a fast spinning crank inside it, witness the tunnellboring machine hard at work matching all the main bearings to the flogged out centre main. The flat 4 configuration is ideal for producing torque. Take advantage of that instead.
Theres a brand new Corolla in my driveway (babysitting for mother in law) at the moment. It just starts to pull hard at 4000 rpm when it starts to sound harsh. I'd hate to hear it at the 6500 redline. But damn it sticks to the road. Its an easy 10kmh faster around my favourite freeway onramp than my lancer. 20kmh faster than the kombi.
tassupervee ·
Corolla at 6500??bwaahahahaha it would only just be exploiting its cam timing by then. rev it to about 7500 and have some fun in it. An engine like that will sit up there in the rev range all day with little ill effects!!!!!
Unfortunately, there is only certain amount of tourque to be had from a single gulp of air and fuel. (no blowjobs here)
Horsepower figures are really derived from an equasion of torque and engine RPM.
So, verrry simply put, if an engine can be made to produce the same tourque figure at so many hundred (or even thousand) RPM higher, it produces more horsepower.
So to get 150BHP/litre even with the best indiction available it is going to take some very fancy induction work and in order to allow that engine to rev enough to achieve that HP. Its going to have to rev it arsehole right off actually.
Single big valves are not conducive to very high RPM and dont flow so well at very high gas velocities, and require very high spring seating and compression pressures to maintain copntrol at high RPM (valve bouncing) and due to this suck an enormous amount of HP just beign driven whereas a heap of small valves are very light and will tolerate quite happily huge RPM's with light seating and compression spring pressuresand are better able to actually allow the flow rates required to get the HP figiures/liter we are discussing.
Put quite simply, revs = horsepower (assuming the induction system allows the flow rates at those higher RPM.
This is exactly why your late model Jap multi-valve iron needs to rev to ear bleed levels to make the power it does.
The make such a good increase in top end that they feel like they have no low down (peaky) but you may probably find that RPM for RPM they are producing still more go (torque) than a dak dak at the same RPM
An engine that pulls well down low at the expense of high revs Ie: a kraut, produces bugger all horsepower.
Bottom line is the only way to increase the tourque necessary to achieve 150Hp/litre without around 10,000 to 11,000 RPM is with forced induction.
Way it goes really!
L8tr
E
Che Castro ·
4 valve engines can and do have low end, 2 smaller intake valves would have more port velocity than an equivalent large single one.
This graph plots the torque curves of exact same engine with 2v vs 4v
Also late model engines also benefit from a variable length intake etc. Variable valve timing/lift can let u have your low end and still have high peak power. This also combines well with a turbo
And the comment about lack of pull in jap engines - I think wes would disagree 🙂
[Edited on 19-4-2004 by Che Castro]
amazer ·
Heeey dont make me sound like a bitch. I dont mean to say that they dont pull at all, I just think, from my own personal experience of driving the jap engines is that the percentage of pull at low revs is minimal to what they have up high. The only exception I have driven is the VWRX notchback with its first engine. That thing was like a tractor. Probably about the same peak horsepower as my fastback but it had it from idle to 7500.
Cam ·
Double overhead cams and 4 valves are an interesting topic. Basically, the main advantage I PERSONALLY :P see is that with bigger valves, you need much, much, much heavier valve springs. 2 small valves need minimal valve return so therefore have less resistance on the motor.
My girlfriends new car is NA, has variable valve timing (fully variable cams), variable intake, hollow cams, etc, etc, etc... With full LA emmission legal induction, noise and pollution. The bent 6 puts out 280BHP at just on 6000RPM. Coupled with very light flywheel, trick trans, carbon driveshaft and so on the power is simply instantanious! Open it in any gear, any speed, any RPM and it puts you hard into the headrest and you stay there!
Granted it's not an SL55. But it also is Aluminium and only has two seats... Therefore considerably lighter than even most hatchbacks.
I also found out that all Japanese cars are, by law, only allowed to be sold with 280BHP max. However, we're going to Tokyo in a couple of months and a trip to NISMO is being organised. Don't worry boys, I checked with the dealer and any NISMO parts and mods are still covered by Aus warranty 😀
What does this relate to a VW motor I hear you ask? Well... The way I see it is; by the time my VW is on the road I reckon I'm going to need atleast 200BHP just to save face. Looks like going turbo will be mandatory :jesus
Che Castro ·
hehe sorry didn't mean to sound catty amazer. I do know what you mean though, lots of jap engines need their tits revved off them to get some power, but i think they are usually in econobox type cars.
dad owns a late model Honda Prelude, its a H22A 2.2L Vtec. Pulls pretty hard from about 2500rpm all the way to about 8000rpm Vtec comes on at about 5500. peak power is about 200hp, and the buildup of torque is progressive and smooth as it spins faster (except when the vtec kicks in). The Vtec thing is kinda silly how it suddenly kicks in, i think its more of a gimmick - other makes have similar variable valve timing/duration that changes continuously.
I think maybe solenoid acutated valves might be whats next. If you need a different camshaft profile, you just upload it to your ECU 😀 There would be no parasitic loss to valvetrain friction, valve springs etc. no valve float.
Cam ·
Yeah, I love the idea of solenoid actuated valves. BMW are developing a motor with them as we speak.