E88 head with F54 block?

[Guest Anonymous]

Hello fellas,

1. I got a E88 head thats been shaved. I don't know how much so my first question would be how can I measure that to find out?

 

2. The guy said that he had installed larger exhuast valves on the head so how do I measure that? I would think that if u installed large exhuast u should do the intake as well. Well give me your thoughts.

 

3. I got a F54 block stock inwhich I plan on using with the E88 head, was wondering if it would be a good combo, what compression would I be looking at, does it just bolt together, and would my valve hit the top of my pistons?

 

3. In general how much hp is gained by 1 compression increase (ex. 8.5 bumped up to 9.5:1)?

 

Thanks,

[DAW]

A very noticable boost in performance will result from raising compression from 8.5 to 9.5:1.

The E88 head has probably had L28 exhaust valves installed which is good to do, and the E88 exhaust valve seats can be machined to accommodate the larger valves. The Intakes, however, are a different story because the valve seats have to be changed to put in the larger L28 valves. With 2800cc, you're going to want the bigger intakes. That's where an L28 head starts looking good because it has the right valves to start with.By the way, the thickness of the cylinder head, from gasket surface (block) to gasket surface (valve cover) measurement is how you determine how much a head has been shaved. The specs for the stock head are available to compare.

I've gone the route you're headed, with a shaved E31 with larger valves onto a L28 block with dished-top pistons...and I was underwhelmed with the result. Consider an L28 block with flat-tops and an N42 or N47 head, which makes almost 10:1 compression; or a set of NISMO European high compression pistons in an L28 block, with a P79 head, shaved a little. This combination has the benefit of a closed chamber configuration which promotes even fuel burn and less tendency to ping than the N42/47 head setups of the same c.r.

There's one other configuration, and I run this on my daily driver. LD28 (diesel, 84.5mm bore, 83mm stroke) block, with it's stock flat-top pistons and 140mm beefy rods, and graft an N42 or N47 head (with the entire intake, exhaust, and EFI/ECU from a 280Z. This takes a bit of work and fabrication such as drilling cyl head bolt holes from 10mm to 12mm and using BMW head bolts, L20B timing cover, drilling dipstick hole in boss of block for your rear sump Z pan, etc. But it does make for a torquey engine and you'll have the only one on the block. Less tendency to ping than the same head on the larger bore, shorter stroke L28 block.

Someone with an L24 might be interested in the E88 head with the larger exhaust valves (although they'd need to notch the top of the cylinder bores with the larger valves). By the way, there are two different E88 heads. The earlier one (fairly rare) has smaller combustion chambers, similar to E31s.

DAW

[Dan Baldwin]

There were FOUR different E88s:

'71 had E31 combustion chambers (42.4cc), and small valves, 10.2:1 unshaved w/ flat-tops

'72 had 44.7cc combustion chambers, small valves, 9.8:1 unshaved w/ flat-tops

'73 had 47.8cc combustion chambers, small valves, 9.3:1

'74 had 47.8cc combustion chambers, bigger exhaust valve, 9.3:1

 

The '73s and '74s are avoided, BTW.

 

Shaving off .040" should get you more than 1 on compression (9.8:1 => 10.8+:1). Wish I had that head dimension handy for you...

 

Dished pistons reduce comp. by ~1.5.

 

BTW, an F54 N/A is a flat-top piston L28, F54 turbos had dished. I'm assuming yours is a non-turbo, right?

 

DAW's right on about it not being an easy task to install larger intake valves. (My info coming from D.L. Potter's reply to a letter in an old ZCar Magazine)

 

Should work fine, though you'll likely be running out of breath above ~5200-5400 with a stock cam and carbs. You shouldn't have any valve clearance issues. I've got KA24E pistons that stick up about .025", and a 290/.503" cam and have not interference probs. Then again my head isn't shaved. Yet.

 

Theoretical hp gain is about the same as the ratio you go up (9.5/8.5 would be ~12%). Consider that the most you could ever get in your wildest dreams with no other changes. Real world maybe 8%?

[Guest Anonymous]

Thanks guys,

I'm pretty sure I got the early E88 heads, I had just ported and polished my intake and exhuast tunnel with my dremel. Man, I had a lot of smoothing to do to the seats underside. It was hanging out like a ridge. Port matched with my gasket, you would be surprise how much of these gaskets are off from the opennings. Exhuast is almost a mirror finish. I'm just going to slap it all together and see what I get. Whatever happens, it should be better then my L24. I will need to get a better cam later.

 

Will that help my breathing from the 5200-5400 u mentioned if I kept my stock carbs?

 

What would anyone suggest I need to have done?

 

Thanks,