shaving my head? (7AFE)

[trdprizm]

Unlike some i dont mind the performance of my 94 prizm, Im going to be doing a 5sp swap so the engine will be coming out anyway and the motor in there is a 1.6. I have an extra 1.8 that I will be swapping in from my old car when I swap the transmission, the performance was a little better to begin with between the 1.6 and 1.8. Now im going to get the head port and polished anyway now i was thinking about getting the head shaved as well to raise up the compression up to 11 to 1. Think that would be a good idea? Im not realy interested in dishing out 600$ + for high comp pistons. I have a intake, header, crank pulley, cat delete pipe. I would think there would be a nice increase in power with everything put on with high compression and a ported head. Think its safe to shave the head to increase compression or is there down sides to this. I dont think i'll need to run octane booster or anything and I run premium anyway so that would matter to me. Thanks!

[punter]

You would probably have to shave off quite alot to hit 11:1, not sure though I've never looked at a FE head properly.

When you machine your head down you slightly alter the timing (as the distance between the cams and crank decreases) This might be as issue depending on how much you take off.

Adjustable cam gears will solve this though.

Also 11:1 will be fine on premium gas. I run 10.5:1 on 98 octane with no issues.

[trdprizm]

yeh I know about the timing issue, but I highly dought anybody makes adjustable cam gears the the FE head. I dont think they would have to shave it that mouch tho, like thousandths of an inch. I think I remember someones sig said they had a shaved head on a 4a or 7afe. Im gonna have to look into cams as well. Webcams or whatever seems like the only people who offer cams for this engine as well. Im lookin into their cams but i dont know if i'll need further modification to the head or if with the upped compression the valves will hit the pistons. Or even if the cams or drop in.

http://www.webcamshafts.com/

[punter]

Originally Posted by trdprizm

yeh I know about the timing issue, but I highly dought anybody makes adjustable cam gears the the FE head. I dont think they would have to shave it that mouch tho, like thousandths of an inch. I think I remember someones sig said they had a shaved head on a 4a or 7afe. Im gonna have to look into cams as well. Webcams or whatever seems like the only people who offer cams for this engine as well. Im lookin into their cams but i dont know if i'll need further modification to the head or if with the upped compression the valves will hit the pistons. Or even if the cams or drop in.

http://www.webcamshafts.com/

ahhhh thats right I forgot about the whole 1 cam gear thing, I'm sure you will be able to find one, or adapt one to suit.

To run that much compression you engine will be interference, but thats no big deal, just put a new cam belt and tensioner on it, and replace it ever 100,000km.

I'd imagine the FE heads are quite restrictive so the would need port work to make any real N/A power. As well as cams.

If I was in your possition I'd just leave the 7afe as is and consider doing a 4age transplant, nothing against FE's but a GE is a much better base if you're after power (especially N/A power)

[94_Rolla_Guy]

if i remember correctly the chambers 32 or 33cc's and the math would need to remove 4cc's if i remember for 10.5:1,

another solution could possibly be what im looking at doing, the 4a-fe and 7a-fe pistons are identical in every way except for the dish the 7afe is 12cc's and the 4afe is 8cc's i did the math to the best of my abilities and came out with 10.3-10.7:1 area if you were to use 4afe pistons in an otherwise stock 7afe....

My problem is that i dont know what i would need for fuel 94octane is hard to come by and expensive so for me the setup would have to run on 91 octane to make it practical for me, please add your thoughts on the matter...

[TheOtherCarolla]

I got a shop to do mine, so im not sure exactly how much would have to be shaved off in mm. I'm running a thinner head gasket as well.

I'f I had to do it again, I would step up from 9.5 to 10.2 or so to 1 instead of nearly 11:1. Your going to HAVE to run premium and probably back your timing off a good bit, which I did.

with 10:2ish:1 you could get by with mid grade gas and prob wont have to fiddle with your timing at all.

Or you could throw some 8.5:1 forged slugs in and spray and pray or go forced induction.

Sure a highcompression N/A FE motor will be snappy, but theres nothing like boost. A few of my friends have srt4s, gsx etc, all are not recored breaking cars, but they deff run off and leave my car.

[94_Rolla_Guy]

Punter: must be nice to get 98 octane over there!!! the only problem is the highest we can get in north america is 94octane and in alot of parts 94 is hard to come by... the best we can really get anywhere is 91 octane..

this is going the same way it has been going before no ones quite sure what will happen in around 10.5 : 1 on 91 octane

Im considering doing it with the backup of being able to use thicker 4age TRD headgaskets to back down the compression to suit for 91 octane fuel...

[punter]

I think we have a different rating system to you guys. I think you 94 octane is the same as our 98.

Our 98 is the closest we can get to the 100 of japan, luckley 20v's don't seem to know the difference.

[trdprizm]

are you positive that 4afe pistons will work on 7afe rods? Or maybe its the 4age pistons im thinking of that wont work without machining. Something about the wrist pin or something? using 4afe pistons would be easier as i will have 2 sets available to me pretty soon, used but I will get them checked out.

On another note, are both 4afe and 7afe heads the same? If i put a 7afe head on a 4afe will it raise the compression or visaversa?

I dont realy want to do a GE swap, i dont care about beating alot of people with it, thats what my camaro is for. This is just a neat little project i want to do. Thanks!