question....ive seen alot of people talking about deleting the IRMC's on the intake manifold...what are they and what do they do? what gain is there from removing them?
Don't bother unless you are modifying thr intake at the same time.
That's what I've come up with.
The IMRC, sit between your intake and heads. There are two ports leading to each cylindar. The IMRC keeps one of these ports closed via a butterly valve that opens at 3500 rpms (thus double air flow when you are supposed to need it). This increases drivability on the lowend, but also serve to be a minor obstruction.
There is probably a good list of mods you'd want to do first. Agan, don't bother unless you arer getting a worked intake (and also a tune if possible). I could also see where it would be OK if you were blown.
That my opinion, with a worked intake and IMRCs, I'd like to see 20rwhp gain across the latter part of the hp curve (more is typical, but I'm conservative in my estimates).
Post a question on this and you'll get smarter people to answer tho.
i took mine to a san diego head shop and am paying 400 for a 3 angle vavle job and 350 for a mild port and polish. i pick them up on the third. i'll let you know how they came out! those prices are total for both heads.
i am doing the clean up in the intake myself, just the upper cover and i polished out the imrc plates and where the intake meets the imrc plates. i didn't touch the runners at all. hopefully i would see some gains off of just the polishing work. i used a basic dremel and didn't take to much material off. just got rid of the rough castings.
Chris, I responded on your other thread about the ARP's.
Make sure your valve guides are good. The typical thing on 32v heads is sloppy guides, bad seals. The exhaust guides usually brown stem the exhaust valve stems and - that's it, bad exhaust valves.
I'd go with bronze guides and seals. If you're going all out, springs retainers etc. I looked at Modular's Performance website and the guides they use are cut down for the custom seal so, you have to buy both from them. If you want, you can replace the guides and use your existing springs if they are not damaged. Most usually put shims under the stock springs for a little more tension. Again, it really depends on what you're going to do. If you're going for 450-500rwhp the stock stuff works pretty good. If you plan on boosting it and cranking up the rpm you'd be smart to go as far as you can while it's apart. The good'ol budget usually dictates how far one can go
If you need to get the heads done give Bob Small Automotive Machine a call. 949-492-0300 He's in San Clemente. That's the shop I build engines out of and he does my machine work there. I do the engine stuff at night. Bob's there during the day. Hope that helps.
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