I have been researching turbo cams for the past few weeks for my 2.0 gsr engine. I have read the arguements that low duration, high lift is the way to go. I have also read that the gsr cams give very good results. The stock gsr cams specs are as follows:

Int-230 dur. / 10.6mm lift
Exh-227 dur. / 9.4mm lift

Now, the gsr cams are supposively "proven" to make more power than say the itr cams. The itr/ctr spec are as follows:

Int-243 dur. / 11.5mm lift
Exh-235 dur. / 10.5mm lift

You can see that there is more duration, but more importantly more lift. These are a very mild all motor cam, and produce a very linear powerband. After looking at Rocket's new m21 cams last night i noticed the specs are as follows:

234 duration 11.6mm lift -intake

I have found out the exhaust specs yet. Now from what i have gathered he put a tad more duration over the gsr cam, and used pretty much the itr spec for the lift. These cams are supposed to the best turbo cam on the market, which is interesting that they dont follow skunk2's or crower's specs:

Skunk2's

Int-230 dur. / 9.7mm lift
Exh-225 dur. / 8.9mm lift

Crower's

Int-240 dur./ .465 mid (inch)
Exh-236 dur./ .445 mid (inch)

Now, researching older posts on this subject Flamenco-T had only the type r intake and gsr exhaust cam, stock gear settings and was making 256whp and 181 ftlbs of torque on 6.5psi with no ebc! Geoff also comment on the type r intake/gsr exhaust cam combo effectiveness. It seems to me that you could use adj cam gears and get the duration down off of the itr intake cam to match rocket's spec. I think that the type r cam might be better than the gsr cam afterall. I would like to hear other's opinion's on this subject. To me both intake and exhaust cams of the itr with the duration dialed out would yield greater results than the gsr cams. They would have the stock gsr's duration, and more importantly the higher lift. Let me know what you guys think.


[Modified by boosted hybrid, 4:06 PM 2/5/2003]

 

Don't know how you can adjust the duration with cam gears...you can adjust overlap, but the duration is controlled by the lobe profile. It would seem intuitive that a lot of overlap in a turbo motor would cause problems, but that is just my speculation...I only have built NA motors.

Kirk

 

ive seen guys pulling over 500 whp with ITR cams, thats why im keeping mine in . i guessits all in how you dial em in with overlap and stuff?

 

Opps, my mistake i meant overlap not duration. I am thinking of getting set of itr cams and having the duration taken down to the gsr specs. I see used sets go for 300-350.00 and a cam grind is 150.00, so for 400-500 i can have a pretty sick set of turbo cams. I am going to check into web cam and inquire about getting the duration taken down. I'd like Earl to comment on this post, he knows about having cam grinds...

 

I want people's input on this. I know someone has to have an idea here...

 

regrinding them sounds like a good idea...

But how much does rocket sell his turbo cams for??

 

I believe the best cam specs for turbo would be on the intake side higher lift with shorter or average duration, and the exhaust side lower lift same duration. All of this is based on the GSR as being the average or basis for comparison. We'll see when you get the exhaust specs posted.

I posted this about a month ago when in conflict with 98CTRCOUPE on comparing Type-R cams with GSR cams.


[Modified by tzsir, 4:35 PM 2/5/2003]

 

The itr cam specs have the lift that you want, but the duration is not wanted. Grinding the duration out of the cam is no problem, its giving the cam more lift that becomes the problem. I would probably choose maybe slightly less duration than the gsr cams so i wouldnt have to take the overlap out as much with cam gears. You would be able to keep the OEM cam reliability, and just modify it a little bit.

 

Rocket's cams are going to be list price of 700.00, then dealers are going to sell them for less. How much less i dont know, but i am guessing over 600.00. I can buy a set of itr cams, sell my gsr cams and get them regrinded and have basically the same cam rocket is selling for around 300-350.00. I am sure everyone on here would jump on turbo cams that work for that price range. Its something to think about.

Its my 1000th post! I am special!


[Modified by boosted hybrid, 6:32 PM 2/5/2003]

 

I just bought a pair of 2001 spec itr cams tonight. I am going to find out within the next day or two who does regrinds, then send them out once they arrive. Cheap turbo cams here i come!

 

 

Let me know how it works out please. I was thinking of getting an ITR cam and doing the same, but using a GSR cam on the exhaust. Turbo's like more lift on the intake side from what I've seen.

 

sounds good. i love saving money too.

 

 

I'm using ITR cams and stock gears and have made 565whp. that doesnt mean i wouldnt have picked up more hp on gsr's with cam gears but i like to keep things simple. stock gears and no playing with cam timing. I'm not lookign to extract every hp out of every little thing on the car either so ITR's have been good for me so far. we will see this month how far into 600whp we can get with them also.

 

i have seen over 600hp on type r cams. good luck motormatrix on the 600

 

..can't let this post die out

 

The cams should be coming anyday now. I am sending them out to web cams for the regrind. I am taking the duration down a bit lower than the gsr's. I dont want to have to dial out overlap.

 

I would be very interested in the results as well. I'm not looking to do anything with my cams right now, hell at this point I just want to get a turbo on my car. What I think would be really interesting would be to do some dyno pulls with the stock GSR cams and then swap out the stock cam and put in the modified R cam and do a few more pulls. Then you could see if you picked up any power, where you mad any gains, and if the total area under the curve increased.

 

I am probably going to do that. The gsr cams are installed in the engine right now. I am goign to break the engine in with the gsr cams, then do my dyno'ing. I will come back and install the itr modded cams, then hit the dyno the next week. I am eager to see what kind of gains they will produce.

 

Thats a good suggestion...Boosted hybrid??? Do you think that this is possible??

 

Unfortunately that is only one way to find out what works.

I have a buddy who made quite a bit of power by actually letting less air in and more exhaust out (gsr intake itr exh) but he had an enormous turbo, and once he went over to rollers even more power was realized. However this was a racecar setup for no street use, so its a very different situation. Also DAYS of dyno time didnt even come close to explaining how much time that car spent on the rollers...

Its very interesting what you have found. I think web may be a great place to deal with, particularly after the luck that the laskey's have had with them. Also the crowers tend to not work quite as well, but make sure you check the LSM clearances!


[Modified by FFgeoff, 12:03 AM 2/13/2003]

 

I plan on dyno'ing them a week apart from each other. Same psi levels, hopefully same conditions.

Geoff, what do you mean by check the LSM clearances? I am trying to learn all the jargon about cams, know of any good sites or books?

 

Good info







[Modified by zip, 4:43 PM 2/15/2003]

 

sorry i missed this post jeff, LSM is a type i meant LSA, lost motion assembly. If they are GSR they bottom out becuase they have less travel then the ITR LSAs. If you use too big of a cam, and it bottoms the LSA out, it can break the cam