Supercharged. Should I stay away from Schrick cams??

[cactus]

That's what the majority of authorities appear to suggesting(from my research), so is this gospel??
I saw a thread where the twin screw actually did better with Schrick cams, but I'm using ASA, which is like a centrifugal.

Please set me right and remove all doubts.

[pbonsalb]

Quite a few people are using the Shricks with centrifugal superchargers. CF units don't build max boost in the peak cylinder pressure/peak torque range, so there is less concern of the extra cylinder pressure bleeding out the exhaust due to the increased overlap from higher duration sport cams. Someone is also using them with apparently good results on a low boost (6 psi) twin screw that does make full boost in the midrange.

They might not be the best choice for a high boost turbo. I think VAC has come out with some turbo spec cams. Could VAC make something more ideal for the CF supercharger than the mild version of the Shricks? Probably, but I am not so sure the mild level Shricks leave enough power on the table in this application to make it worthwhile.

Philip Bradley

[marc1119]

Get the Schrick 264/256 cams..They make a nice mid range and top end difference....~ 15 RWHP and 10 RWT across the board..not just at one peak value...

Get them.....

edit..OOPS did not notice you had a Euro engine

[cactus]

My motor is the Euro S50B30. VAC and Bimmerworld has the Schrick 284duration(inlet and outlet) and 11.9mm lift Schrick cams. Is that too much overlap?
I'll be revving to 6000rpm on most days.

Turner has 284intake and 274exhaust Schrick cams(not sure of the lift), will these be any better?

[Def]

You probably don't need cams on your Euro engine. You have a large enough duration and lift on your stockers that they are probably not causing the intake valves to get anywhere near choking.

I'd look into trying to drop the compression ratio some and running more boost if I was going FI on an S50B30.


US S50/S52 engines will see a benefit with cams since their head/cam combos flow less than Euro engines.

[pbonsalb]

I don't know too much about the Euro motors except that they use about 1000 more rpm and have more radical cams to help them breath at that rpm. Cams probably would not be my first mod. As Def points out, more boost might be the better choice.

Often, tuners will choose a cam that favors the exhaust over the intake on a naturally aspirated car that is converted to forced induction. In other words, if you have a range of cams to choose from, you might want to go more radical on the exhaust than on the intake. This is a less desirable alternative to choosing exhaust valves that flow more in relation to the intake valves than the stock ones. Forced induction motors usually benefit from a higher ratio on the exhaust to intake flow. I have not seen anyone apply this theory to the FI kits installed on BMWs, so you might want to do some more research to see if there is a reason why (like the exhaust side of the head already flows very well relative to the intake).

Philip

[cactus]

Thanks a lot guys. I'll put the cam upgrade on hold for now. I'll look into doing a pulley change for more boosting.

The stock Euro cams have a 260 degree duration and 11.3mm lift, so it might be adequate afterall.

[pbonsalb]

Your CR is higher than what we have here in the US on our E36M3, so be careful about raising the boost too much. The tuners here who do the E46M3 kits -- which has similar CR to your Euro E36M3 motor, use 5.5 to 6.5 psi max boost. One shop set up a car with 7.5 psi, but it had a lot of supporting mods.

You can drop the CR with a thicker HG, but that usually requires a retune because it usually has an adverse effect on detonation resistance and thus ignition timing. You can also improve the exhaust with something like the Supersprint full exhaust system. And the cams may well be a good choice -- I would try to find someone who has done cams on a supercharged Euro motor first. Frankly, if I was pulling the head for a gasket change, I would do the cams then if I was going to do them at all -- much of the same labor is involved. The same goes for headers -- if the head comes off, that is the time to install Supersprint or other headers.

I wish I was starting out with 286 hp before adding boost (or 321 or 333 hp).

Philip

[cactus]

Phillip, I do have a full Supersprint Euro M3 exhaust system(headers, racing midpipe, and muffler), so I know breathing is ok(sounds awesome too).

I can get some lower compression forged pistons(8.5:1), I'm actually presently in discussion with a UK vendor about some Wesico forged pistons.
I contacted JEpistons also, but they say I would have to send them a sample piston as well.

So if I can drop the compression with the pistons, I can boost more, which would be sweet as the car is flying now at 0.5 bar.

[pbonsalb]

Sounds like a lot of fun. Building an engine with lower compression is not cheap, but if you can afford it, the results are better than just the thicker headgasket because squish is unaffected in the combustion chamber and that can allow you to retain more timing.

Think carefully about how low you want to go on the compression. The CF supercharger is not like a turbo, where full boost is all there in the midrange and cylinder pressure is very high. I am not an engine builder or a mathematician or engineer, but I think a CF supercharged motor can use more static CR than a turbo motor when both have the same peak boost. You may not want to sacrifice the edginess of the motor by going to 8.5:1. For example, 9.5:1 may be a better choice for, say, 15 psi. Some people here are running 11 psi with their 10.5:1 CR USA motors without any problems.

Wiseco is in the US. You may not need to go through a UK vendor. With some searching, you may find someone who has already rebuilt a Euro motor with lower CR pistons and a piston maker than has the design ready. Diamond, JE, Wiseco, Arias, etc. It is worth trying since you probably do not have a spare piston and don't want to disassemble your motor before you have to. When I sent a piston to Arias, it took months to get the new set.

Philip

[cactus]

Thanks Pliilp. I appreciate evry word of advice that you have given me.

The UK people just put me through to Wesico in the US. I guess they can get the piston specs from their UK link.

I'll speak to them about a CR of about 10:1 then(I believ the stock CR is 11.5:1).
I already spent some $$ buying forged conrods + bearings and a lightweight forged crankshaft so forged pistons is not out of my way at all.

Going this route will allow me to just use the stock HG and have a rock solid bottom end.

The only person in the Western hemisphere I know that has boosted a Euro S50 is the Azevedos, and they are too busy to answer my dumb ass questions.

[pbonsalb]

I might use a stock thickness HG, but not a stock one if an MLS is available for your motor. I don't know if there are differences in the motor that require a different gasket. Maybe a company like VAC in the US that has some experience building race motors is familiar wih the Euro motor?

You may be causing more problems that you will have to address later. Will that supercharger you have handle more boost? Will your intercooler be sufficient?

Keep us posted here on your developments, especially if you get some dyno runs. If I ever go back to Jamaica, I'll send you a message first. I was there in March of 2005 for a week of vacation.

Philip

[Def]

I think 9.5:1 is a good target for static CR as was already stated. You can go pretty high on 10.0:1 as well, but if you want lots of power you'll be limited. 9.0:1 is good for about 16-18 psi on 93 AKI pump gas. Guessing you won't go that high on a CF SC, so somewhere in the 9.5-10:1 range sounds good to me.

[cactus]

Thanks guys. I'll start looking into all your suggestions.

I emailed Todd at turbochargingdynamics.com, he has a good hookup on MLS gaskets and ARP bolts.

[agu845]

Only semi-related (as I have US-spec engine), but Im getting a set of these Schrick's for my TS'd car.

[cactus]

I saw a dyno result somewhere and there was a huge improvement(20-30hp I think) with a twin screwed SC setup with Schrick cams, so I think it's definately worth the upgrade.