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Fuel injection question.
I am fabricating an oval track car and am wondering which fuel injection system to run. I know that many different variables effect my choice, but I was wondering what you guys think. Here's the specs. I Have a 1.8L with stock rods, stock crank, Wiseco forged Flat tops (83MM). 14:1 compression. 110 degree lobe center cam with a power range from 5500-8400. I plan on topping off at 8200. I have a 83 GTI head. I am not allowed any porting or polishing. Must retain stock sized valves. Now for the quesion: What should I have CIS or CIS-E? I am also running Unocal 76 leaded race fuel. I am looking for a trouble free system that is easy to tune without going excessively lean. I have alot of experience with Weber DGV series carbs, but the throttle body looks so much larger that I would like to go with that route. I can use ANY VW parts to construct my car so are there any certain years or models to look for? The basic rules are no porting or polishing intake or head, no oversized valves, and no cam with a lift more than .510". Other than that anything goes.
I would really like to hear your opinions...
Scott
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I'm not a CIS-E guy, but I was under the impression that the only thing it really bought you over regular CIS was the knock-sensor. If you stay FI, you'll want to use the larger A2 GTI/GLI throttle body (they're also on Audi 5000's). I would suggest sending the injectors to someplace like Marren Motorsports in Ct. to have them blueprinted.
I assume the pistons have valve relief cut into them, especially if you're running that kind of compression and that kind of lift. You're definately going to want to run HD valve springs at that kind of lift and rpm.
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MARRS #25 ITB Rabbit GTI
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Scott, I would probably suggest the mechanical CIS as the CIS-E, I believe, uses an oxygen sensor with a control unit that regulates a frequency valve on the metering unit. The frequency valve basically controls the system fuel pressure so the control air to fuel ratio is maintained. Since you are using leaded race gas, the life of the oxygen sensor would probably be short lived.
On my SCCA production Wabbit, I use the mechanical CIS with an adjustable, converted Control Pressure Regulator (CPR)(aka warmup regulator). Normally the CPR is electrically heated, and the bimetalic strip bends as it is heated, thus increasing the control pressure as the engine warms up. On a cold start, the control pressure is lower, resulting in a richer mixture until the engine becomes warm. I totally removed the heating strip and made the bimetalic strip (or arm) adjustable vertically so I can adjust the control pressure to whatever value that I want. With some testing, I have found the best control pressure, for my SCCA road racer, is about 42 psi to 46 psi versus the stock pressure of 48 psi to 52 psi. The lower control pressure results in a richer mixture throughout the rpm range.
If your rules permit, also look at getting a VW Euro metering unit as the walls of the air sensor funnel are steeper, resulting in a richer mixture at Wide Open Throttle (WOT). Also get the air sensor plate that is 80mm in diameter as some of the plates are 60mm in diameter.
With lower control pressure, an Euro metering unit, and a late model throttle body, you should have enough fuel. Be sure to install an EGT probe(s) and gauge to measure exhaust temps so you can tune the control pressure.
Good luck with running stock rods with 14:1 compression. Let us know how that works out. Regards, Ryan ([email protected])
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Scott, I would probably suggest the mechanical CIS as the CIS-E, I believe, uses an oxygen sensor with a control unit that regulates a frequency valve on the metering unit. The frequency valve basically controls the system fuel pressure so the correct air to fuel ratio is maintained. Since you are using leaded race gas, the life of the oxygen sensor would probably be short lived.
On my SCCA production Wabbit, I use the mechanical CIS with an adjustable, converted Control Pressure Regulator (CPR)(aka warmup regulator). Normally the CPR is electrically heated, and the bimetalic strip bends as it is heated, thus increasing the control pressure as the engine warms up. On a cold start, the control pressure is lower, resulting in a richer mixture until the engine becomes warm. I totally removed the heating strip and made the bimetalic strip (or arm) adjustable vertically so I can adjust the control pressure to whatever value that I want. With some testing, I have found the best control pressure, for my SCCA road racer, is about 42 psi to 46 psi versus the stock pressure of 48 psi to 52 psi. The lower control pressure results in a richer mixture throughout the rpm range.
If your rules permit, also look at getting a VW Euro metering unit as the walls of the air sensor funnel are steeper, resulting in a richer mixture at Wide Open Throttle (WOT). Also get the air sensor plate that is 80mm in diameter as some of the plates are 60mm in diameter.
With lower control pressure, an Euro metering unit, and a late model throttle body, you should have enough fuel. Be sure to install an EGT probe(s) and gauge to measure exhaust temps so you can tune the control pressure.
Good luck with running stock rods with 14:1 compression. Let us know how that works out. Regards, Ryan ([email protected])
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Ministocker,
Does your series have a website or classifieds? I have a set of 82mm Wiseco flat tops and a Cat cam w/ a lift of .510" I have no use for. Your series would be perfect for these. Sorry to interupt your discussion. I'd go with the cis or a weber DCOE setup.
Steve
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88 ITB Scirocco
www.geocities.com/highspeedconnectionracing
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Actually, my track has a website. WWW.Racingonline.com/jefferson It's called the "International division". It got it's name because most tracks up here only let american cars into ministock racing. Jefferson lets in the foreign cars also. We are acually faster than the hobbystocks and Sportsman cars and only 1 1/2 sec. slower than the late models. We simply corner better than a big long car on the quarter mile.
Thanks alot guys...
Scott
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Scott,
I've got to jump in here too and follow Steve's lead. I've got a 90.5 forged stroker crank, a set of forged 82.5mm pistons and rods (individually) balanced, and a 1.7L VW block that's been bored to 82.5mm (what the crank/rods/pistons came out of).
I have no use for this stuff anymore, and would like to turn it into something I can use on my current race car (like money!). If you've got someplace where we can advertise this kind of stuff, that would be great!
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MARRS #25 ITB Rabbit GTI
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Actually, I may be interested in some of these parts. Please E-mail me with prices. I am the only person up here with the VW fever, so the rest of the guys would be more interested in your Pinto parts. Please Email me with what you have and the prices you're after.
Thanks,
Scott
[email protected]
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Bill and Steve,
I'm planning some ice racing this year (if the lakes ever freeze) and might be able to use some of those engine parts. Don't want a repeat of last year where I wasted a perfectly good IT engine. :{ Please email me if you still have them. I think I know where Steve is located. Bill, what State are you in and can you further detail specs?
TIA,
Eric
[email protected]
