z-ya

Will need lots of compression on that mic. I'll try to capture the sound.

Engine in car, and running. Sounds nasty with the megaphones. Hope to do a practice day on the 30th. Photos of exhaust to come later.

To be honest, I would go with a P90. It has the chamber shape you want for flat tops, and milling/shimming are relatively inexpensive to do. The cost will be the port work that needs to be done on the P90. But that may actually cot less than welding and shaping the chambers of your E88. And, you could probably sell that E88 to someone looking to build a hot street engine. Plus you will save on pistons and piston machine work. What is the stroke you will be running?

Duplicate

I have a set of Arias L24 pistons that have a dome for the E88 valve configurationn. They may be able to make you an 88.5mm set with your pin height. But, you will still need to check all the clearances and potentially have to do additional machining to the piston domes to clear the valves and head. The other option is to have flat tops made, and switch to a P series head. You can shave and shim the P series to get the CR you want. You still may still need to machine reliefs in the flat tops depending on how much you shave the head and the lift you are running.

If you need some hotter plugs I've got boxes of BPR4ES-11 and BP5ES-11. I'll never use them.

First choose the CR based on what fuel you will be running. Pump (93) gas stay with 10:1 or lower. This is especially true with an E88. If you need to raise the CR, cut the head and or use a thinner gasket. Then shim the cam towers accordingly. Making custom pistons for an 88.5mm bore and valve reliefs for an E88 will be difficult. Even after making them you will need to check valve to piston clearance and may have to machine the valve reliefs more. You have to account for rod stretch at high RPMs when checking both valve to piston and piston to head clearance.

Given that all cars in this race were not equal, it was all driver. One is not better than the other, it is all what you are used too, and what you make of it.

Sorry for such a late reply, but I learned a new way to check cam timing from my engine dyno guy and thought I would share it. It only requires and accurate timing mark on your damper, and it assumes the inlet and exhaust lobes are the same profile for your cam. It won't tell you the advance or retard in degrees just lift. The lash needs to be set correctly. You can use the piston stop method Paul describes earlier in the post and a degree wheel to determine if you timing tab is accurate or not. Imagine a cylinder of the engine at TDC but not in compression, but on the other stroke--overlap. Both that cylinder's valves will be open some amount. To measure those amounts set up a dial indicator on the closed inlet valve's retainer, zero it, and carefully bring the engine (turning it in the normal direction of rotation) to TDC overlap for that cylinder. The valve will have opened some amount. The indicator will tell you how much. Now, without rotating the engine, transfer the indicator to the exhaust valve retainer on the same cylinder and zero it. Once you are zeroed turn the engine in the normal direction of rotation until the indicator stops moving. The exhaust valve will have finished closing. The number on the indicator now is how much the exhaust valve was open at TDC. Compare the inlet and exhaust numbers. If they're the same the cam is neither advanced or retarded. If the inlet number is bigger the cam is advanced. And if the exhaust number is bigger the cam is retarded. There probably shouldn't be more than .005" difference between the numbers. This method requires only an accurate TDC mark on the crank to work. Don't retard the cam without checking piston to exhaust valve clearance VERY carefully. For that matter don't advance it much without checking piston to inlet valve clearance. This is mainly if you are running a high compression engine with small combustion chambers and domed pistons. Remember that a small error in the TDC mark will double it's effect in the lift difference number. You can still get these from Nismo I think: http://www.courtesyparts.com/nissan-motorsports-adjustable-cam-sprocket-s30-p-227555.html?cPath=7724_7758& You can advance or retard in 3 degree increments. It is what I used on my recent build.

Do you have an IAC valve in there? Is the MS controlling it or is it just plugging a hole?

Not sure if anyone asked this, but did you put the breather screen back in the block? Just another thought.

0.028" is too small a gap for such a low compression motor. Try running a 0.040" gap. You should be using BPR6ES-11(projected tip) or BR6ES-11.

What plugs are you running? What do you have them gapped to?

All E31, E88, N42 and N47 heads have the same length valves. The P79 and P90 have shorter valves (intake 113.1, exhaust 113.9). Where and how are you measuring length?

Maybe you didn't read the entire thread? Yes, of course, I did check the wipe pattern, and a 0.170" lash pad produced a good wipe pattern on all cylinders. The cam and rockers are fine, as they survived almost 2 days on the dyno. What was wrong was the rocker arm geometry due to the fact that the head has longer than stock valves. Longer valves will allow more lift. The head was not built by me, but someone from Bob Sharp Racing. I don't have the original cam, so I had Isky grind me one.. I do have the lash pads that were run on the head. So I shimmed the cam towers another 0.034", and now the original lash pads (0.210) give a good wipe pattern on at least one valve. The geometry also looks better where the rocker meets the lash pad.

OK, I'm pretty certain we found the problem. You know what happens when you ASS-U-ME. All looks good with guides and valves as expected. Except, exhaust valve length is 119mm. Mmmm, 3mm longer than stock. Looking closer at the geometry when the valve is closed the surface of the rocker tip that is touching the lash pad is almost on the casting. There is barely any clearance between the retainer and the rocker. In fact some of the rockers have a little groove worn in that area. When I got the head, the cam towers were not installed, but there was a bunch of cam tower spacers in the "bad day at the track" box. I measured the stack of front shims (the only ones that are different), and it measured 0.072". The head is shaved about 0.055", and they used a stock head gasket. So I calculate that the shims should be 0.055" for stock valves. The cam towers were shimmed 0.017" more to account for the longer valves (if my assumptions are correct). I'm running a 2mm gasket, and had shimmed the cam towers 0.017" to account for the thicker gasket and head shaving. This would have been OK for stock valves. 0.025" would have been exactly correct but I didn't have the right thickness shim, so I went with a set of 0.017" shims from the stack I had. So to keep the geometry the same I should shim the towers 0.025" + 0.017" = 0.042". This make sense?

I forgot that I used 3/8" ARP rod bolts with Carillo rods. These also torque to 60ft-lbs. 9mm ARP bolts for the stock rods should be torqued to 44ft-lbs.

If the compressor was leaking oil you would probably see it on the plugs.

Probably not a good idea to spin the turbo without oil pressure. Maybe the turbo needs a new shaft and seals at this point.

It might be the turbo, but when I had a turbine seal leak on my turbo car, it smoked all the time, especially under load. It was so bad I couldn't drive it. What ring configuration are you running? The race motor I just built was still smoking a little even after two days on the dyno. When I pulled the head, I could see that the rings hadn't fully broken in yet. You can tell by the wear pattern on the cylinder walls. I'm running a total seal moly top, two piece 2nd, and standard oil control ring setup. It is making good power and ~250psi across all cylinders. Did you check the compression yet? Pete

We are running a Datsun competition style 6-3-2 header with dual 2-1/4 pipes to either Magnaflow glass packs and straight pipes exiting out the center, or megaphones. We will be able to swap the glass packs for Megaphones at tracks that allow those sound levels. Kind of like this:

Sounds good. Great job! Keep the revs up during initial break in. Also, you may want to use some RedLine breaking additive. Good stuff.

Here is where the rest of the car is: Scott at Ballistic Motorsports is doing the exhaust for us.

They are pretty deep steel retainers: ~0.170" lash pads give a good wipe pattern with the cam I'm using.

Pulled the head today. No piston damage. I'm having my machinist check the guides and spring pressures again on that cylinder (#2). Stay tuned...