Author Topic: Can any one help me with cams.... (Read 4003 times)

ZeroG · « **on:** March 13, 2007, 01:45:10 AM »

Well a couple of years back I repalced the cams on my FI car with ones that were increased duration and lift. I went with 272 x 10.5 on both the exhaust and intake side. I make decent power out of a 4 cyl. car 209 RWHP and 178 RWTQ.

Now I replaced the cams at the sametime I did a complete rebuilf on the top end. Prior to the rebuild the car was making 171 RWHP and 167 RWTQ. The car is very peaky as your can imagine with the cam set up that I am currently running. I was speaking with someone the other day and he said with the set up that I have there is too much overlap and that it is costing me a lot of TQ. He believed that if I replaced the exhaust cam with the stock one and then kept in the intake cam and just rolled it back a little bit I would get a more well rounded engine with top end power and low end torque.

Anyone have any thoughts?

Stock cam is 245 x 9.5 I believe..

nickmpower · « **Reply #1 on:** March 13, 2007, 02:09:00 AM »

yeah if there is too much over lap the the supercharger will just push the air in the intake valve and out the exhaust valve

ZeroG · « **Reply #2 on:** March 13, 2007, 02:26:22 AM »

Quote from: nickmpower;21178

yeah if there is too much over lap the the supercharger will just push the air in the intake valve and out the exhaust valve

That is exactly what I was told. He said you may see 10 PSI of boost in the manifold, but in actuality half that boost is probably going in one side, and then right back out.

So what do you think should I swap the factory exhaust cam back in and retard the intake? What kind of a difference in performance should I expect?

nickmpower · « **Reply #3 on:** March 13, 2007, 02:41:13 AM »

you would want to advance the intake and retard the exhaust right? ill think about it tmr when ive had more sleep

romkasponka · « **Reply #4 on:** March 13, 2007, 03:00:21 AM »

My frend has audi2,2 20V 5 cil. turbo, camshafts is 280/280 EDIT (278/260 at 0,3mm lift). Power 450-600, depending from boost.

if you want rev your engine up to 7-8krpm you should use big duration..

Try DynoSim2003.

You better check http://www.catcams.com for camshaft setup.

ZeroG · « **Reply #5 on:** March 13, 2007, 07:59:43 PM »

What is the verdict? Should I drop the stock exhaust cam back in and leave the intake cam and see what happens?

Quote from: romkasponka;21181

My frend has audi2,2 20V 5 cil. turbo, camshafts is 280/280 EDIT (278/260 at 0,3mm lift). Power 450-600, depending from boost.

if you want rev your engine up to 7-8krpm you should use big duration..

Try DynoSim2003.

You better check http://www.catcams.com for camshaft setup.

nickmpower · « **Reply #6 on:** March 13, 2007, 08:38:31 PM »

have you upgraded your exhaust after you put the supercharger on? If so and you noticed a gain, i would say leave it where it is or play with the adjustment of the cams. WHere did you get your cams btw?

romkasponka · « **Reply #7 on:** March 14, 2007, 05:02:11 AM »

in catcams turbo engines exhaust cam have about 10deg less, so..

You can regrind it..

ZeroG · « **Reply #8 on:** March 15, 2007, 12:05:42 AM »

Quote from: romkasponka;21272

in catcams turbo engines exhaust cam have about 10deg less, so..

You can regrind it..

That is a little bit on the permenent side for me right now. I' think I'll put it together as is, and then if I get ambitious swap the stock exhaust cam back in take it to the dyno and see what happens. If results are good, I might consider a regrind.

Thanks fior the info...

Quote from: nickmpower;21253

have you upgraded your exhaust after you put the supercharger on? If so and you noticed a gain, i would say leave it where it is or play with the adjustment of the cams. WHere did you get your cams btw?

Well I have always had a CAT back system. I replaced the header with a Superspring replica 4:1, and then added a CAT bypass track pipe and it felt a lot faster. I did not get a chance to take it to the dyno, but it was faster for sure.

Which is right to my knowledge with cars with overlap. I was told that it is OK as long as the cyl has a means to get rid of the extra exhaust.

I purchased the Cams from BMP Design. They are decent quality, and even have a German part number on them. I would not be surprised at all if they were Shricks minus the name. I mean they're only so many cam companies out there, and I know BMP is not one of them.

romkasponka · « **Reply #9 on:** April 20, 2007, 12:09:54 PM »

http://www.catcams.be/800x600/prod01Adata.htm?PN1301522?PN13014xx.js

ClubSport · « **Reply #10 on:** April 20, 2007, 10:09:31 PM »

Quote from: ZeroG;21177

Well a couple of years back I repalced the cams on my FI car with ones that were increased duration and lift. I went with 272 x 10.5 on both the exhaust and intake side. I make decent power out of a 4 cyl. car 209 RWHP and 178 RWTQ.

Now I replaced the cams at the sametime I did a complete rebuilf on the top end. Prior to the rebuild the car was making 171 RWHP and 167 RWTQ. The car is very peaky as your can imagine with the cam set up that I am currently running. I was speaking with someone the other day and he said with the set up that I have there is too much overlap and that it is costing me a lot of TQ. He believed that if I replaced the exhaust cam with the stock one and then kept in the intake cam and just rolled it back a little bit I would get a more well rounded engine with top end power and low end torque.

Anyone have any thoughts?

Stock cam is 245 x 9.5 I believe..

First I'd try playing with your cam timing. Maybe retard the exhaust cam. You can get rid of 5 degrees of overlap that way.