TCD S38 kit??

[BMWS38]

So after reading the post about Kens turbo monster I was wondering... Since I have no where near 70k to drop into my ride, and since I really don't require 700hp, what would be the chances of TCD engineering a kit for us M5 owners. I don't have the mechanical skills or time to peice one together, but I would love to have a boosted M5, and within reason I could justify spending some money on my baby if it was well engineered... what do you guys think?

[Boru]

We previously offered to design a kit if we had 5 or so people commit (ie. cough up funding) to buying. We didn't get the 5 people. Maybe another time around...

[M635CSi]

Let's start with the exhaust manifold...

How much will the manifold cost if we could get 3 or 4 people to make a deposit?

[T_C_D]

Let's start with the exhaust manifold...

How much will the manifold cost if we could get 3 or 4 people to make a deposit?

$795 with a commitment of 5 people.

Todd

[BMWS38]

Is it possible to have a low boost application with stock internals? If so what type of power figures would you expect?

[Duke]

Is it possible to have a low boost application with stock internals? If so what type of power figures would you expect?

I bet you would be in the high 300's. Would not think any more than 6 psi of boost though. If you went stand alone ECU, you could go higher boost. Then if you added water injection, more boost. The C/R will be the limiting factor in the end.

[Matt]

Let's start with the exhaust manifold...

How much will the manifold cost if we could get 3 or 4 people to make a deposit?

$795 with a commitment of 5 people.

Todd

Wow. You cant get factory manifolds for that, much less euro headers. If you had 5 orders, what would an NA bundle-o-snakes cost ?

[Jeremy]

Is it possible to have a low boost application with stock internals? If so what type of power figures would you expect?

I bet you would be in the high 300's. Would not think any more than 6 psi of boost though. If you went stand alone ECU, you could go higher boost. Then if you added water injection, more boost. The C/R will be the limiting factor in the end.

The m30b35 has the same static compression as the North American s38b35 at 9:1. The M30b35 guys can run 12-14 psi intercooled safely on stock engine management (not sure about non-intercooled). I'm curious to know why you think an M5 motor would be any different? Are you thinking of the 10:1 M88/3 or is it just because you're considering a non-intercooled setup?

I'd think they could run at least 10psi intercooled.

Jeremy

[Duke]

I was thinking 10:1 C/R.

9:1 C/R would support 12 or so psi.

[bmwmike]

Itll be tough to get 5 people to commit. Personally I dont see how boosting an S38 could be a good idea, unless you did spend a lot of time and money on the engine. Its already very strung out, so obviously low compression pistons and a rebuild would be the first thing to do. And having 6 throttle bodies would probably require a lot of extra headaches for a f/i application. Once you do have it setup, tuning would probably take a very long time which again means a lot of money. Of course it can and has been done a few times now, but I doubt any of the people who have done it could tell you it was cheap in any way. I suppose if you did a very low boost setup, like 4-5 psi it may not be so expensive. Id rather build up an M30 and try to get some crazy numbers.

[bmwmike]

The m30b35 has the same static compression as the North American s38b35 at 9:1. The M30b35 guys can run 12-14 psi intercooled safely on stock engine management (not sure about non-intercooled). I'm curious to know why you think an M5 motor would be any different?

C/R in the 3.6 is 10:1 and in the 3.8 its 10.5:1

The M30 and S38 are completely different engines. One has a single cam and has been around since the ice age. The other is DOHC, has 6 throttle bodies, and has a stock rev limit at 7250 rpm. People have over revved them and blown them, can you imagine how much easier it would be to destroy the engine under more abuse.

[Skeen]

C/R in the 3.6 is 10:1 and in the 3.8 its 10.5:1

The M30 and S38 are completely different engines. One has a single cam and has been around since the ice age. The other is DOHC, has 6 throttle bodies, and has a stock rev limit at 7250 rpm. People have over revved them and blown them, can you imagine how much easier it would be to destroy the engine under more abuse.

I promise you Jeremy (and everyone else here) knows the difference b/t the S38 and M30. He was comparing the compression ratios of the two to provide a reference point for people when thinking about the S38. He's not talking about the S38B36 or S38B38 that you mentioned, either.

Running conservative boost and limiting the revs shouldn't be a problem for a healthy motor. I don't see why you think having 6 throttle bodies would make it more difficult or why tuning would be such a problem. Should be similar to any other motor in that respect. I think you're right that it won't be cheap, but neither is any turbo project.

[M635CSi]

I've suggested starting with the exhaust manifold as a jumping off point; mission creep will follow... The $795 price seems fair... In the absence of a group purchase, "plan B" is use a tubular manifold (header) porting to the turbo and out through a single 3" exhaust.

I actually prefer the packaging of the M30 engine; it’s simple, direct and lends itself to better low and midrange power but the four valve motor is just so cute to look at even if all those holes in the cylinder head do weaken it. Also, in the M635CSi, the four valve engine is perceived as "better" fitting the car.

Inline six cylinders are inherently low (relatively) RPM engines so I would think an 8,000 RPM redline would be the limit for the street. Can't really imagine how someone would need to spend $70,000 to get 700 horse power out of these engines but that may say more about pricing than costs.

600hp at the crank should be a no brainer for these engines. Making power is always easier than keeping the engine together, so a stand alone fuel/ignition is a must and perhaps some emergency cooling in the form of fuel or water/alcohol injection. The challenge is getting the fuel/ign maps right, if they're wrong, the strongest most expensive parts in the world won't hold things together.

To make the M88 engine live under boost, I would install sodium exhaust valves, stronger (longer?) rods, forged pistons, piston squirters, replace bolts with studs, o-ring the block and blueprint/balance the engine. A dry sump pump/pan and billet crank would also be nice-:)

[Tammer in Philly]

Inline six cylinders are inherently low (relatively) RPM engines so I would think an 8,000 RPM redline would be the limit for the street.

I'm curious about this comment. I-6 motors are harmonically balanced and inherently extremely smooth, which is a bonus for high-rpm operation. RPM limitations come from longer strokes, weaker valvetrains that allow "float" at high rpm, and so on ... why would the I-6 configuration be a detriment? The only inherent weakness in an I-6 is the relative length of the block, so you have longer rotating components (cams/crank). Remember, in 1985 the M88's nearly 7k rpm cutoff was considered very high-revving indeed, while current M3s roll out of the door with a factory 8k rpm cutoff.

Care to elaborate?
-tammer

[M635CSi]

Inline six cylinders are inherently low (relatively) RPM engines so I would think an 8,000 RPM redline would be the limit for the street.

I'm curious about this comment. I-6 motors are harmonically balanced and inherently extremely smooth, which is a bonus for high-rpm operation. RPM limitations come from longer strokes, weaker valvetrains that allow "float" at high rpm, and so on ... why would the I-6 configuration be a detriment? The only inherent weakness in an I-6 is the relative length of the block, so you have longer rotating components (cams/crank). Remember, in 1985 the M88's nearly 7k rpm cutoff was considered very high-revving indeed, while current M3s roll out of the door with a factory 8k rpm cutoff.

Care to elaborate?
-tammer

Hi Tammer, crankshaft whip is worse in the inline 6 cylinder engine than a shorter more rigid design. Yes, 7,000 RPM in '85, and 8,000 RPM in '06 is impressive. Bear in mind though, small block 302 cubic inch Chevrolets put together by teenagers were spinning (momentarily) to 10,000 RPM with not much more than stiff valve springs 35 years ago...