This is the most interesting post in Circuit Racing for a while. Lets keep it to constructive advice and opinions rather than let it degenerate into a stroker vs stock session.
I raced with Jak and his stroker engines of various capacities. His engine was no less reliable than mine.
As others have said the heads and cam can make or break the combination.
I picked my level 5 DRD heads from aircooled.net on the promise that they had good air speed. I thought the 40 x 35.5 and the smalll mini-D-ports would suit the capacity.
I also wanted to keep the valve train conservative with lift and valve diameter (weight) yet long duration. That's why I chose the Engle 130.
I was disappointed by the heads. But the combo seem quick for what it is. The main problem is fuel stand-off at 2500rpm due to valve overlap or an ineffiecent exhuast or something. It makes the fuel curve really rich and occasionally the car hesitates.
Whenever you're in a 60 zone, which is most of the time, in 4th it's always on 2500rpm or there abouts.
My combo is similar to Stan's combos. He's probably the way to go. But my advice is to stick with his formulas, specs and head recommendations. Don't deviate.
So wether we go for a stroker or a 1776,1916 i think? we all agree that its the combo you chose and the application that makes the difference.
ie reliable street power, no stress low revs maybe 2176,2332.
compition under 2000cc well maybe thats were the little 1916 shines.
I dont know about whether a 1916 or a stroker will have any affect on gear changes though.I mean if anything a stroker will pull you out of a slower corner with more drivability than a high strung 1916 combo.
So lets dream a little.
My dream street motor,
94mm pistons and barrels
84mm berg crank
fk 87 cam with straigh cuts
my cylinder heads and rocker gear(sorry secret squirrel info)
comp ratio 11.0-1
my 48idas and manifolds (again secret squirrel)
msd 6al with billet dizzy 2 step launch
and of course my good freind larry to build it ,
yeah, we must not forget there was once this almighty stroker that dominated hillclimbs too tho.
it's still around waiting for a dreamer like me with a wild set of throttle bodies to add an E8, do the check through and fire it up........funny how dreams turn to reality before you know it😏
and no there won't be a build up thread this time around🥲
dumone wrote:yeah, we must not forget there was once this almighty stroker that dominated hillclimbs too tho.
it's still around waiting for a dreamer like me with a wild set of throttle bodies to add an E8, do the check through and fire it up........funny how dreams turn to reality before you know it😏
and no there won't be a build up thread this time around🥲
Now this sounds interesting? *enter fishing smiley here*
the car was a green one me thinks and it was piloted by a mad man way to much mullet involved. however wit was before its time, only a few boys were capable of the HP and track setup at the time all cred to who where involved!!!!!
Might be a sidetrack, but I just had a thought. If you are serious about racing, picking your class can really help a lot. I entered a motorkhana a month back in a very crappy hatchback aiming to win my class and succeeded. I was not the most powerful car in class and I had buggered shocks and street tyres but I won anyway. Why not try entering the 1301-1600cc class and stick with a really tight 1600 and work hard at competing within the class. It would certainly be cheaper partswise and a lot nicer on your gearbox. Remember the porsche salzburg rally beetles were using 1600s and getting 120hp (flywheel?) at 6500rpm. All the specs for them are on the web. If you want to ungrade to a larger capacity class you can do it later. Worth thinking about I reckon. 😉
i'm always welcome to throw money into any off these bottom less pits, some needing more than others, all needing good time. i have sure learn't a lot just looking and talking. Getting your hands in there and having a go is the best way.
Hey Daimo, one day a very long time ago, like about maybe 10 years Greg Bendl Adam Hamilton and myself took Hellbuggy up to Willowbank to race at the Flat Fours Jamboree.It was totaly rained out so we came home the next day to Tamworth,Adams beetle broke down so Greg towed Adams car home on the trailer leaving Hellbuggy at my place for a few weeks.
Now i can tell you i am not one to pass up a oppurtunity so one quiet Sunday afternoon i fired up Hellbuggy and went for a blat up the street.Light weight buggy frame, 1998cc Jeff Unwin Hellbug motor, well just use your imagination.
If I ever went with an NA motor path again id be looking at the QSC (http://www.qscusa.com/vwparts.htm) aluminium nikasil cylinder. Run some wiseco's in them, some ported heads, FK8 cam, balanced crank, H beams and 12:1 - 12.5:1 CR. Add some italian 44 IDF's or EFI and youve got an easy 140-150hp, and reliable too.... to a degree. It would be an engine i'd like to see.
Geez! this thread is shedding a bunch of light on a previously dark area for me, i met Stan a couple of years ago, we pulled into his place with the intention of a quick chat (now I know) and advice on where to go for bits and pieces, i realise there are many respected and qualified motor builders, but Stan just struck me as one of the most helpful blokes around, (how cool was that aircraft engine? magnesium this and titanium that?) i know where i'll be taking our 61 bug and it's tired old 1600 twin...how much did you say? allowing for gearbox condition. cool thread, keep it going.
Geee Whizz! That 6k i had saved is already spent, now for gearbox, suspension, brakes..What's the turnaround time on a Pobjoy build fellas? Never one to rush a good job, looking at next year round Feb- March. And what sort of punishment will a standard gearbox take when hooked up to a Steroid donk? Gearbox rebuild costs? Cheers for all the info. Adam
Sorry Daimo, i meant that the 6k i had clear in the Dub acount has been allocated to a Pobjoy donk, just need to find the time to get down and see the Man. Poverty is owning several dubs! 🙂 Happiness is driving em
Twin plugger might take it over the 6 grand mark i reckon...here's hoping, you can bet i'll post pics when it's in...probably not till after Xmas though.
Whats with the twin plug head setups ive heard so little about...? Is it an effort to get a better burn when your using a head thats been semi-hemi cut to lower the compression? Has anyone done back to back dyno/emissions and mileage comparisons with the 2nd plug turned on and off? Im just thinking why go to so much effort when you can just plug in a 55KV CDI multi-spark system for much less effort.
VWCOOL wrote:Stan Pobjoy does twin pluggers in his aero engines and in his top-end street and hillclimb motors... has done for several years. It seems to work okay
Yeah I understand in an aircraft situation for redundancy it is required, but from a performance perspective I do wonder what the benifits are and how well they are documented. From what ive read of the semi-hemi head cut it does lower the efficency of the combustion chamber vs a kidney shaped chamber. Semi-hemi was mainly done to lower the CR while maintaining a close deck and was done on largish displacement engines, particularly turbo. Aparently Gene Berg was a fan of the semi-hemi but many other big names out there are just as against that design. Twin plugging may well fix the poor combusion burn issue through the combustion chamber of a semi hemi. If there is data it would make for an interesting read.
Craig Torrens wrote:I'm just thinking why go to so much effort putting twin turbo's on a vw motor when you can just put a turbo subaru motor in it for much less effort.😂
HA HA... I wasnt taking a shot at twin plugging, infact im all for modifying the hell out of something if it makes a measurable improvement. There in lies my point..
Also, subaru engines cant displace nearly 3lt... where as a set of 104mm barrels and some autocraft heads on my current bottom end will. Mmmmm displacement!
it's not just redundancy; two plugs help the combustion 'pulse' across the crown of the piston where a plug isn't centred particularly well. Good for torque.
I've not been witness to any dyno tests, but if I disable the second coil on my Nissan, it slows down...
VWCOOL wrote:it's not just redundancy; two plugs help the combustion 'pulse' across the crown of the piston where a plug isn't centred particularly well. Good for torque.
I've not been witness to any dyno tests, but if I disable the second coil on my Nissan, it slows down...
A nissan with twin plug combustion chambers? Whats that?
I've got twin plug heads on a Pobjoy motor and I've tested it with twin plug ignition and with a single plug ignition and I dynoed the results using a G tech Competition meter. I won't post dyno results because it's would be way to easy to fudge the results on the G Tech plus it doesn't really compare to anything.
What the twin plug does is make a cammed up motor a pussycat to drive. The cam in my motor starts at 4g and pulls to about 7.5g with the right heads etc.
Without the twin plugs the motor needs more revs for everyday driving as you would expect with such a cam. I found when I had single plugs I was using a lot more revs between gears in everyday driving, typically I wouldn't change below 5g. I reinstalled the twin plug setup and suddenly you've got torque off idle and around town I change at 3g or less, and the topend remained the same.
As far as semi hemi heads go I doubt Stan has ever used a set as I know he doesn't like them.
sorry, didn't mean to start this up here.................it would be nice to see some pics posted up for all to see and consider (i have actually checked them out)...........i doubt for the price and acurracy Stan does the conversion, anyone would be silly enough to copy them
