Stock 98 shortblock with AFR 205's milled to +/- 62 cc (still at the machine shop initially CC'd at 67.45 havent gotten final results yet), and graphite 98 head gaskets which I think are .053 comp thickness. What kind of compression would this net with a 228/232 on a 112 +4 XER lobes? I havent ordered or decided on a cam yet, so those specs arent set in stone just a ballpark figure. Any suggestions on the cam or what compression I should try to achieve with these heads and running CA 91 octane? Car is a M6 DD full-bolt on minus electric water pump. Thanks for reading.

 

forgot to mention looking for around 450 rwhp and not spinning past 6200.

 

Just fill in the blanks.


http://www.rbracing-rsr.com/compstaticcalc.html

 

using that calc I get a SCR of around 10.6-.7. got a DCR calculator?

 

Set your compression first then have the cam spec'ed accordingly.


I'd shoot for 11:1 to be safe, some of my customers like 10.5:1 to be safe.

The cams job is to fill the cylinders with air not keep them from getting filled.

 

Well said. Took me a long time to figure out what you just put into a few words.

 

Ok so my comp is going to be 10.7:1. Is there anything wrong with the cam that I posted in the first post?

 

Were in the same boat. First, I would be suspect with the original CC measurements as AFR 205's are suposed to be 66 cc out of the box. Since I also have to run on CA 91 octane fuel, I asked Tony from AFR what he recommended for CC's on his heads. He recommended 62 CC with a .040" head gasket for CA 91 octane fuel. If you do a search you will find his "Formula" for a 400+ HP C5 that he ran. Give him a call. Hes a great resource and easy to talk to.

Mike V

 

In addition the AFR's have a double quench pad which also helps iirc, Mamo is a great source of knowledge and AFR heads are right up there in the tops.

 

Once you decide on a scr (def go with the .040 cometics) and cam i can give you the dcr.

I also run the afr's with .040's at 11.82 scr and a 8.7 dcr. runs great

 

well the SCR is going to be 10.7. I already bought the .053 headgaskets so I'll be using them. Cam and pushrods are all I need to start the build. Im going to keep hit high 220's low 230's to ensure enough PTV clearance. What would be an ideal cam for that SCR? I know if you run too large a cam without a enough comp you lose low end tq.

 

The stock mls gaskets are like $20 a peice but the cometics are 160 a pair. but you can run more scr with less prone to detonation.

It is free hp sell those gaskets and get the .040's if you want all the hp for every dollar spent.

I was running a 232/234 xer .595/.598 and took out my buddies dynoed 620hp 502 crate moter with a 100 shot. that was a great cam that had good low end pull.

 

I am going with a very similar setup. My custom cam was spec'd at 226/232 and my stage 2.5 5.3s have a 62cc chamber. I am using .045" cometics and getting about an 8.6:1 DCR and if I remember right a 11.1:1 SCR. I am spinning mine to 6500rpm and setting the rev limiter at 6700. I am shooting for ~420rwhp and ~440-450 with a FAST intake.Its going to be VERY drivable and may even handle a small shot of N20 later.

With a 98 for sure upgrade the rod bolts and dont worry about spinning it. It should be safe up to ~6700rpm.

I got the cometics for about $140 for the pair, like quick346 said it allows more compression with less detonation and better quench.

If you have any questions about my setup or need any info on getting good parts for good prices feel free to PM me id be happy to help.