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Blowers on high compression engines?

H

Heywood

Hard-core CEG'er
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Jan 24, 2006
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Hope this is OK to post in the FI section since this doesn't really relate to the Contour.

I'm looking for my CSVT replacement at the moment and I'm tempted by a few high compression N/A engines, although they are a little low on HP. I'm wondering about getting the car and adding a supercharger to up the HP. What are the problems/issues? I gather that the returns may not be as high as for an engine with lower compression.

[Specifically I'm looking at 2009 C series mercedes - The C350 fits the bill at 280 hp, but doesn't come in manual, so thinking about a C300 but it has 40 hp less. Also considering the 3.2L Audi A4. Compression ratios between 11 and 13]
 
The ONLY way to make it work is E85 or 118 octane racing fuel ( that may not even do it ). It will be a detonating mess with any boost and pound the bearing out of the connecting rod in no time. Cylinder pressure has to be controlled so precisely that dropping forced induction on any newer vehicle with high compression is a receipe for disaster.

Ford Ecoboost has 10:1 compression ratio, direct injection, and 2150 PSI fuel pressure to control detonation. It has 365 HP with only 12 lbs of boost. I think they rate it close to 400 HP with E85 in testing.
 
Thanks for the responses. Was only think between 5-8 psi. I know that detonation is the problem. Is retarding the timing a long term option? Would it be possible just to get different cams, or is it necessary to change/modify the heads to reduce the CR?

On the audi, they make a FI version of the 3.2 for the A6. I would have to do more research to confirm its the same block, but I would guess so - maybe just different heads, or would they change the stroke too?

You are confirming what I thought initially - that it may not be feasible/practical unless I get into tearing down the motor. Sad because I like the cars (will probably still pick one from A4 or C350) but I love the whine of a screw.
Just read a little piece on water injection - sounds simple but what are the drawbacks?
 
Timing won't help much, if any. Detonation occurs when the ignition is caused by excess cylinder pressure and happens even before the spark is fired. A diesel engine operates this way.

Water injection will help however you are taking power away from the engine at the same time since water doesn't burn.

Bore, stroke, and cam timing are used by the engineers to get the exact cylinder pressure and piston speed they need to have max torque and minimum exhaust emissions.
 
Considering you are interested in an A4 have you thought about a 2.0t? With a chip and turbo upgrade you might be where you want to be.
 
RFcsvt said:
Considering you are interested in an A4 have you thought about a 2.0t? With a chip and turbo upgrade you might be where you want to be.
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Have given that some thought too - would be cheaper up front as well. I know its a stupid prejudice but to me 2L is a huge turnoff. Not to say its off the table - I just like the idea of more displacement.
 
If you want more power get the nicer versions of those cars: S4 or C class AMG. Sure they are more expensive but you are going to be tacking on another $5-10K at least to add FI to a non FI car. Get an older version of the S4/AMG to save some cash. Older B7 S4's have 340hp and go like stink. They can be had for near or under 20k now (I owned one for a while). Now I have a Jag XF Supercharged which I bought used for a great price. You can get the 09 Jag XF SC for 25-35k now which is a scorching deal for what you get (420hp and every option). Find one with a 100k warranty like me and you'll be very happy. 2010+ have 470hp but price is quite a bit more.

Tacking a FI kit on to a foreign car is not cheap (big $$$$).
 
Heywood said:
Have given that some thought too - would be cheaper up front as well. I know its a stupid prejudice but to me 2L is a huge turnoff. Not to say its off the table - I just like the idea of more displacement.
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I get the displacement thing. Take one for a spin if you get a chance, they are pretty impressive for a smaller engine.

Blackcoog makes some excellent points about the performance models of the cars you are looking at. A B7 S4 with exhaust is great. For some reason the V8 sound from that car is so uncharacteristic, I love it.
 
I just discovered something that I'm a little disappointed I didn't know. The E90 BMW 335i has a twin turbo 3.0 inline 6. I believe they run about 25k which is half of what an E90 M3 would cost. I don't know how you feel about BMW but a TT 3.0 sounds like an appealing start considering it is 300 hp stock.
 
The S4 and C63 models are just a little outside my budget. Plus on a car where maintenance/parts are expensive I don't want one with higher mileage, especially a sport edition that's been beaten on for all those miles. Trust me - a C63 is what I'd love to get but that little responsible part of my brain just won't let me pull the trigger :(.

I know about the 335 - BMW is off the table for me. Every review I've looked at for these cars compares to the BMW and says its the winner but they just don't do anything for me.

I think in the end I'm going towards a C350 with paddle shift auto.
 
If and when you get a C350 it would be cool to hear what you think of it. I've kind of been thinking of the future and which car to replace my DD with, however for me it's not going to be real soon. I like the 335i and the C350, for some reason the A4 doesn't do much for me so I know what you are saying about how you feel about the BMW. I can't seem to get over the 08-10 VW Passat 2.0T either, I have an 06 now and despite the issues I had early on I really like the car and probably wouldn't hesistate to get another one if the price was right. I wonder what tuning options are available for the C350? A tune and exhaust might bump it up enough to add some fun and keep it reliable.
 
The wife and I drove a 08-09 C300 AWD a we really didn't like it. The wife didn't want RWD so the C350 was out. That C class has a very boring interior. The exterior looks great but they are bare bones inside to keep the price down. We also didn't care for the BMW due to the bla interior and exterior. We ended up with a 09 Maxima SV. The new body style is beautiful inside and out: 290hp, CVT, NAV, 19" stock rims, moonroof, aluminum paddle shifters, low miles, warranty, etc. The new body style looks great (GTR inspired) and the handling is superb. Great car. It's surprisingly quick (0-60: 6.1 sec) with that CVT. Don't write them off. Read a review on them.
 
RFcsvt said:
I just discovered something that I'm a little disappointed I didn't know. The E90 BMW 335i has a twin turbo 3.0 inline 6. I believe they run about 25k which is half of what an E90 M3 would cost. I don't know how you feel about BMW but a TT 3.0 sounds like an appealing start considering it is 300 hp stock.
Click to expand...

The 335 (and 535) also respond very well to mods. Tune/Downpipe/Meth injection and they easily make 440+ to the wheels. Can be very quick cars.
 
bhiggs89 said:
The 335 (and 535) also respond very well to mods. Tune/Downpipe/Meth injection and they easily make 440+ to the wheels. Can be very quick cars.
Click to expand...

That's pretty impressive. I used to be a huge BMW fan and this definitely renews my interest.
 
bhiggs89 said:
The 335 (and 535) also respond very well to mods. Tune/Downpipe/Meth injection and they easily make 440+ to the wheels. Can be very quick cars.
Click to expand...

I really don't see how that's possible unless you are boosting the crap out of that car. You are saying they get nearly 200 wheel hp from a tune, exhaust, and meth injection. That's on a stock motor with the turbo pushing what...40psi?
 
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