Engine/Speed Mods to a Chargecooled S4

[benfell100]

Talking of engine mods, I am considering removal of my air-con compressor and plumbing the chargecooler through the rad ala Sport 300. I never use it and it doesn't work well anyway. I have the car booked in for an electric chargecooler pump as mine has done the usual.
I have thought about head porting and polishing but haven't heard anyone do it, how much it cost and what improvement it made. I would do it if it were straightforward and the guy knew what he was doing with a 910. Also considered the injectors from John Welch in the US.
I have done the ram air mod which was fiddly but do-able with a thin bendy arm and an eye on a stalk.
Got the dump valve, PUK chip and AP brakes, any other suggestions that won't break the bank?

[rlearp]

I wouldn't bother with injectors - I've dynoed my car (90 SE, 3" open no cat, T04 turbo, 1.2 bar boost, nitrous, ram air) extensively with various modifications and it is always safely rich with the stock fuel system - even when flowing nitrous. Upgrade your turbo, it isn't that expensive (if you take it off and send to be upgraded), around $500 should do it even if you pay too much.

R

>> Edited by rlearp on Monday 28th June 16:54

[karmavore]

After a chip, what the single biggest bang-for-the-buck horsepower mod you can do to a 910?

Luke.

[lotusguy]

karmavore said:

After a chip, what the single biggest bang-for-the-buck horsepower mod you can do to a 910? Luke.

Luke,

I would say a port/polish job. It will make the most of virtually any other mod you make.

If you ever saw the intake manifold off the car and matched it against the ports in the head, you'd see that there is at least 1/4" to 3/8ths" of material to be removed from the head ports to get a match. Given the size of the intake runners, this has to account for at least a 15%-20% increase in the size of the head ports which of course allows that much more fuel/air to be introduced with each intake stroke. Polishing (smoothing is a better term) will allow for much better flow.

Unfortunately, what with removing the head, replacing the head gasket, not to mention the cost of the porting work to begin with ($700-$1,500) it is also one of the most costly mods. But, in this case, you really do get what you pay for. Happy Motoring! ...Jim'85TE

[f1karting]

Jim.. ever thought of matching the intake runners to the head instead? I wonder just how much the port runners themselves are the restriction. Perhaps by matching the intake manifold to the head you could eliminate the nasty entrance losses, gain flow, and save cost. I have used "JB Weld" to reprofile manifold interiors with good results.

Has anyone actually flow benched a head before and after, without touching the valve throats to see just how restrictive the runners themselves are? Perhaps eliminating the mismatch is the biggest "improvement" where the most obvious fix has been to open the head up.

my 0.02.. Jan 83ET

[benfell100]

Thought about the turbo too but WC-Eng' wants $1600 plus the old one and PUK wants a similar amount in Euros, plus the old one.
Porting/polishing sounds interesting...
Before anyone says it, I have a performance driving course booked at Hethel in September. Can't wait.
Still fun tinkering with the car though.

[NJGSX96]

karmavore said:

After a chip, what the single biggest bang-for-the-buck horsepower mod you can do to a 910? Luke.

After the chip, the best bang for the buck modification would be to increase the engines breathing. Ram air mod with K&N filter (or your favorite air filter) followed by a full exhaust (2.5-3 inch) with either a hi-flo cat install or no cat and a better flowing muffler.

[rlearp]

Benfell,

Can you remove the turbo yourself? Or pay someone to? Then all you need to do is send it to Turbonetics or Turbocity, etc, and have them upgrade the compressor side of the unit or whatever you want. It isn't that expensive and you'll have great results. Many have done it here that way, I just bought a brand new turbo in the trim I wanted, T04E-50, and put it on - cost was about $500 plus a lot of sweat and work. I detailed some info about it on another thread.

[lotusguy]

f1karting said:

Jim.. ever thought of matching the intake runners to the head instead? I wonder just how much the port runners themselves are the restriction. Perhaps by matching the intake manifold to the head you could eliminate the nasty entrance losses, gain flow, and save cost. I have used "JB Weld" to reprofile manifold interiors with good results. Has anyone actually flow benched a head before and after, without touching the valve throats to see just how restrictive the runners themselves are? Perhaps eliminating the mismatch is the biggest "improvement" where the most obvious fix has been to open the head up. my 0.02.. Jan 83ET

Jan,

The intake runners are much larger than the ports on the head, by at least 1/4" circumference. I don't see anything being gained by downsizing these to match the head. Happy Motoring! ...Jim'85TE

[rlearp]

If the runners and head are as mismatched as Jim says (not had mine off yet), then some simple blending here could help and you could do that on the car.

Pull the intake and get a clear shot at the head. Turn the motor over so the cyliner you are working on is on the compression stroke, all valves closed. Stuff the runnerwith oily towels/rags/etc. that YOU CAN retreive and that block metal shavings getting into the head. Start blending the mouth of the head to match the runner diameter and repeat for other cylinders. Use a shop vac to make sure no pieces are left. I've done this a lot and never had a problem, just take your time.

If there is indeed a "step" then you can gain a little by removing this step and blending for smooth airflow into the head.

R

[benfell100]

Forgot to mention, mine has a stainless sport exhaust, K&N and the ram air mod done so it breathes pretty easy.
I guess the better turbo is the way ahead, that and my electric chargecooler pump.
I was thinking of adding water wetter, anyone use this? I would expect only to see a reduction in temps using freescan but it must be good for the engine.
With all these mods done it should absolutely fly...
Dom

[lotusguy]

benfell100 said:

Forgot to mention, mine has a stainless sport exhaust, K&N and the ram air mod done so it breathes pretty easy. I guess the better turbo is the way ahead, that and my electric chargecooler pump. I was thinking of adding water wetter, anyone use this? I would expect only to see a reduction in temps using freescan but it must be good for the engine. With all these mods done it should absolutely fly... Dom

Dom,

I use WaterWetter from Royal Purple. A noticeable reduction in temp on the gauge, albeit slight. Still, I think it's worth it (a little spendy), but really just, if it goes up even a couple of bucks, I'll probably stop using it as the car operated fine re. temps before. It's just a little bit better now. Happy Motoring! ...Jim'85TE

>> Edited by lotusguy on Wednesday 30th June 12:34

[rlearp]

Like Jim I noticed a little temp change on a few of my cars, a couple of degrees C. I use it in the Lotus, in the coolant and I'm fixing to put a bottle into my chargecooler coolant as well. Sort of one of those non-tangible improvements, but like I said, there was a little reduction.

R