Here is the AMR500 Supercharger that I have installed onto my MegaSquirted 1915cc Scat engine in my 1972 Superbug. This engine has twin single 50mm
throttle bodies, twin wasted spark coils, toothed wheel and crank sensor, and a cold air box breathing through the engine lid. For those who said
this engine is too big, well you were wrong. With a 3:1 pulley ratio I get 2psi at idle (with the BOV vacuum tube disconnected), 5psi by 1500rpm, 6psi
by 2500rpm and lifting to around 6.3psi by 3500pm. It then holds that level of boost to 4500rpm. So far I haven't revved past 4500rpm as I am still
sorting the drive belt, inlet air temps and tuning. Using math calculations this pulley ratio should give me 8.3psi of boost but due to the VW
aircooled engines old design, I believe that I am getting around 79% volumetric efficiency thus the lower boost pressure. My engine recently pulled
78hp at the wheels (naturally aspirated) at Leon's Motors Dyno Day and I am hoping for around 105-110hp at the wheels (135-140hp at the flywheel) now
that it is blown. Certainly feels like it in the mid range on part throttle. The engine is very responsive and feels like a 2.5L engine but without
having to rev it. I love it. I am even getting used to the whine from the blower. Now if you wanted more boost from an engine this large (or larger)
then you are out of luck as this is the limit for the blower pulley size and also the limit for the blower speed given my 5500rpm rev limit. There is
a throttle butterfly in the intake to the blower that is controlled by a vacuum actuator which closes the intake when idling, cruising and under
deceleration. This also helps in reducing the blower noise. I am working on adding water injection to reduce the intake temps. They are around 90-130C
on a 20C day. The temps spike when the throttle is closed. This is because the BOV (or bypass valve) is of a plumb back design and blows back into the
blower intake pipe. This means that the heated air is going back through the blower for another turn thus heating it again. I am thinking of plumbing
the outlet of the BOV to a pod filter. This should help to lower the intake temps as well.
Talk to you all later.
David
Great
Very interesting. Like to read more on the build.
Are you running heater boxes on this?
Hi Bizarre,
Yes I am running the original heater boxes. I modified an Empi GT Two Tip exhaust by cutting it off at the end of the extracta part and then
fabricating a 4in muffler with baffles and the 2 1/2in twin baffled tips. The build-up of my car and engine (minus the blower) can be seen on my blog
http://george1972superbug.blogspot.com.au/2012/05/where-do-we-start.html
Looks nice in there mate. Over 100hp in a bug would be quite tidy.
Here are the muffler parts.
I wish I new how to post more tha tone picture with each post.
I need to watch my spelling also. Sticky keyboard is the problem. Or I am getting too old.
Hi David, just checked out your blog, and while it's not all "my cup of tea" I love how you've done it all "your" way and I love that you've
fabricated pretty much everything from scratch, must have taken some time.
Well done.
Dave,
Awesome work do you mind if i repost your pic on my FB page?
Dave,
Awesome work do you mind if i repost your pic on my FB page?
Thanks Gracey. I was trying to modernise my Beetle and make it better and safer than when it came out of the factory in 1972. I love being able to
tune the engine from the drivers seat (or my lounge room for that mater) and to be able to make improvements based on data logs. It also makes for
something different to the normal thing that you see in most Beetles. I was originally building the car for my kids, but I took too long (4 1/2
years), went too far and now I don't want to give it to them. They are allowed to drive it though. My 21 year old daughter just has an Auto Only
Licence so she just comes for rides when she is free but my 16 year old son thinks it is cool. He is on his Learners and is looking forwards to
driving it even more now that it is blown. I see that you are not that far from me. I live in Toowoomba. Might see you some time.
Hooroo all.
David
No problems Paulc. Go for it.
David
Very nicely done, will definatly get around to reading your write up
Spent some time today fitting the water injection reservoir. I used 90mm PVC piping, blanking caps and a 90deg bend to form the reservoir. A VT-VZ
Commodore washer motor, a cone spray nozzle (with built in filter and anti-drip valve) and hosing were used to spray the water. The pump will spray
170ml/min and it wll be fitted into the blower inlet pipe. I will use the Megasquirt to turn on the pump (via a relay) at a combination of 1psi and
110C. I am unsure of what the results will be but hopefully tomorrow I will know.
David
Sorry, I forgot to tell you where I fitted it. The reservoir was mounted under the rear floor above the gearbox. Some rough measurements show that it
will hold around 3L water so if the pump was on all the time (extremely unlikely), it will run for around 17 1/2 minutes before running dry.
Time for bed I think.
Hooroo
David
mmm.... just had a quick flick though your blog
Very interesting - need to read more
Especially need to go back and read about the head liner
Do you have more pics of the interior??
Yes I do Bizarre. Send me a hello to my email and I will send what I have.
thieledj@optusnet.com.au
If anyone elso wants some more photos, then just email me with your requests.
Thanks to everyone for your kind words.
David
Looks interesting. How will the blower cope over time. I was led to believe an AMR500 will need to be pushed hard for a 1600. I have 2 amr500s at home and hope to put them into my baja when it's done. I have gone 2 cause i thought theat they wouldn't need to work as hard for boost. Now need to check your blog. Neat install, well done!
Hi Baghall,
Being a factory fitment blower originally built for a Nissan (and built by a reputable Japanese company - Aisin), I am hoping it will last for quite a
few years. I have made the whole installation reverseable so I can go back to normally aspirated with only a few hours work if it all turns pear
shaped. If you believe what you read on the net, this blower is capable of a sustained 16000rpm and brief runs to 18000rpm. With the 3:1 pulley ratio
that I am using, the blower is spinning at 2850rpm at idle, 5400rpm at 60kph, 9000rpm at 100kph and 15000rpm at my self imposed 5000rpm engine rpm
limit (the Scat made max power at 4900rpm). The blower does sound like a cat in a blender most of the time. This noise could also be louder in my
application because I have it plumbed as a blow through setup. This was becaused I was already running twin 50mm throttle bodies on each side of the
engine. I think that if it was pumbed in a draw through setup, it would be quieter. By having the blower spinning so quickly from idle, I get awesome
pull from idle and in the lower rev range. So far I mostly change gears by 2500-3000rpm (still tuning and need a stronger clutch) and I am
accellerating a lot way quicker than when the engine was NA and reved to 5000rpm. This low down grunt means that I don't have to rev the engine hard
to get rapid acceration. For a race car this would not be as useful but in a streeter it is exellent.
I think that twin AMR's would be awesome (I advised a mate with a black Baja to do the same instead of going for an SC1200). Yes, the revs would then
also be lower or the maximum boost available would be greater. It would be your choice.
Hooroo
David
My blog does not include the blower installion at this point in time. Still in progress.
I have now installed the water injection system. The first spray nozzle was supplying 200mls/min. This was too much. It certainly did lower the air
temps but could be felt cutting in. I now have a nozzle that only supplies 55mls/min. We will see how it performs on the weekend.
Hooroo all,
David
Quote: |
Thanks Joel,
What is the link to your thread?
David
I had to go to the crypt to find this one
http://forums.aussieveedubbers.com/viewtopic.php?tid=65678
This is such a neat setup I felt the need to comment on how much I like it.
I will be taking a few cues from your car when I get my superbug finished and get onto supercharging it.
There have been a few changes to the setup for my blower conversion. The basics are the same but the throttle body placement and inlet plumbing has
been changed for the better.
Scat 1915cc, Megasquirt ECU & custom fuel injection, E85 fuel and AMR500 supercharger. Made 116hp at 4900rpm but had a minimum of 110hp between
4000rpm and the rev limiter at 5700rpm. Maximum torque ran between 2500rpm and 4000rpm and peaked with around 525lbs of tractive effort. As a
comparison a standard 1600DP makes 38-40hp and 250lbs of tractive effort on the same Dyno. After the Dyno session I found a loose L/H inlet manifold
plus on the data logs the air-fuel ratio was in the 10's (quite rich) above 5000rpm so there may be more in the old girl yet.
That's cool. Good work!
Mmm... Very Nice...
R_E_S_P_E_C_T!!