z-ya

Thanks John. CR will be somewhere between 12 and 13:1. I'm looking for reliability first, so I'm going to start at 7000RPM redline. I'll do my best to build it to support 8000RPM, but I may never run it there.

This is a build thread, so maybe the admins want to move it to the members project area. The main goal of the build is a super reliable road race L28 engine. I want this engine to last for years, so it is not being built for all out max power. The other goal is to use as many of the Bob Sharp engine parts that I have acquired recently. Basic engine specs: - Max RPM: ~7000 - Max CR: ~13:1 - Bore/Stroke: Stock stroke/0.020-0.040 over bore - HP goal: 250WHP Some of the Bob Sharp parts I'll be using: The is sorta what it will look like: I have these headers, collectors and twice pipes. Carbs: Probably the middle damper: Valve cover: E31 head: And a bunch of other stuff including a remote pickup oil system including competition pan and oil pump cover. I plan on making this build thread as detailed as time will allow (got to get it built by next spring). Stay tuned. Pete

What got "toasted"? If you are doing a budget build, just use stock L28 rods, crank, and only bore if you need to. Chances are, there is nothing wrong with the bores. If the pistons have detonation damage get a set of aftermarket L28ET pistons. If you need to bore, you can get +.5 and +1mm over sizes. Also, when you bore to 89mm, you can't use the stock head gasket. You have also taken away a lot of metal which in a turbo applcation is not good. You want the block to be as rigid as possible. Pete

Looking great Ron! The heater hose arrangement looks like it was designed like that from the factory. Much better than in my RB swap, and actually looks a lot better than the stock L6 configuration. Pete

30% loss? I think you need an oil cooler!! But seriously, a good example of how 1/4 mile calculators can be way wrong.

I stand corrected! Cool, never seen one make that much. I'm not a fan of using time slips to determine power. To many variables. Your 2+2 is quick (not too pretty, but fast). I remember you doing a 100 or so runs at the drag strip in San Antonio. You were getting the most out of it for sure. Gave Art Singer from Nissan Sport a ride on the track in Nashville this year: This is what he said about my 180WHP track car: It always feels great when a Corvette has to point you by. Took him a couple laps to figure out that there was no way he was going to loose me in the turns.

Yes, but that much difference? Your saying a 3% increase per point, so the total if everything is the same would be 4.5%? Where did the other 15% come from, tuning? Yes I agree, the stock CR motor had and AFR of 12:1 at peak power where the higher CR motor had a AFR of 14:1 at peak power. You might be right, but I don't think that increasing the AFR by 2 points is going to gain 15% on that motor. Again, I have never seen a stock motor make over 140WHP. That stock 10:1 CR L28 will make 160WHP all day. I think the better test would be to use a flat top 10:1 CR motor and do the same test you describe above. Because the increase in CR in the 10:1 motor will yield less HP lost per degree of timing pulled back. The timing on the stock CR motor was 34 degrees, and the high CR motor 28. Both had stock ignition systems (280Z). Premium unleaded (93) was used in both engines.

Paul, I agree with a lot of what you are saying, but I'm an Engineer, and I like to see actual measurements. Seat of the pants, guestimates, and rules of thumb mean nothing. Show me actual HP measurements that compare the following: L28, dished, N Series head (set timing just below detonation threshold) L28, flat tops, N Series head (set timing just below detonation threshold) Our club has done a lot of dyno days. Here is an example of a 19% increase (same day, same dyno): Stock N42 engine (fresh rebuild), headers, EFI, 2.5" exhaust Flat tops, N47, headers, EFI, 2/5" exhaust I've not seen a stock N42 block/head combo that made more than 140WHP. Have you? Pete

If you have to shave a head that much because of warpage or detonation, you should find a new head. If you are shaving the head to increase CR, you should shave as much as you can compensate for when you shim the cam towers to keep the rocker arm geometry correct. If you need a higher CR, per Jon's suggestion, either weld the camber to reduce volume, or you can also run domed pistons. Pete

Paul, you know (from previous discussions) that I don't completely agree with you here. Yes, you have to run less timing with an N4x/flat top combo, but there are still significant power gains with increasing CR over just head work. In fact, it is a much more cost effective way to build power for NA applications (sorry, I know you build heads for people). For turbo, P-series only. Now if you combine the proper head work (this is where your craftsmanship comes into play), cam, N-series, flat tops, and 10:1 CR you can run 34+ degrees advance on 93 octane pump gas all day. I know someone with that exact configuration, and it's seen many races. I'll take a higher CR with choice of cam over head work with choice of cam any day.

It all just bolts in. Do the work yourself and learn. It's empowering. You will not be disapointed. Do the research, take your time, do it right.

I don't know what brand. The ones I have are 133mm and came from a bunch of Bob Sharp stuff I got.

These look almost identical to some rods that I picked up. Seems like a good deal to me. They are stock L28 length, and require floating pin. So you need to run forged pistons with these.

Deck height is determined by block height, rod, piston, and crank, not the head gasket thickness. The stock deck height (the amount the piston protrudes above the bock deck) for an L28 is 0.030. I think the test you did is valid. Did you have the timing set installed, or did you just rotate the camshaft?

Sounds good. Tune it with the lowest octane rating you plan on running on a regular basis. Standard bore? 81' blocks had dished pistons, right? If that is what you are running then the CR should be around 8.5:1. With flat tops around 10.2:1.

er Yes, not a crazy CR. I have a new set of 15:1 pistons that have been shaped to match the head chamber that I can use. I'm going with flat tops. I'm not looking for a 1-2 race engine with max power. I want a reliable 5+ year race motor. One of the BSR boxes I have is what I call a "bad day at the track" box. I'm not looking to have another one.

Sounds like you have been thinking about it lot more than I have. Tony's advice is worth listening to. I'm no expert, but I plan on using this head on a 12:1 87mm L28. According to Todd at Wolfcreek, it should be a good match. And since the head, intake and carbs came off the same GTU engine, I'm confident it will make good power.

No, that is some sort of BRE replica. Nice car though. It was at this years convention. You know, the 40th anniversary of the Z car? There were three #33s. The twin turbo plus a C production car, and GTU 280Z. Also the Steve Millen #75, which we got to see on the track.

Sounds like a top fuel car: As of this year the car hasn't run for 30 years.

I know exactly where they are: This is one of the spare Nissan V8s used in the Newman-Sharp 280ZXTT IMSA car. It uses Kinsler MFI. It's a ***** to tune. An expert is required. We had it on the track at the National convention this year in Nashville. It's sounds awesome, but wasn't really running right. The other Bob Sharp cars to use injection were the Z31 single turbo cars driven by Newman and the Z32 twin turbo. The single turbo Z31 cars used a heavily modified stock ECU. JR Mitchell told me it was a real hack, it it took them forever to get it running right. Good enough to win 2 or three championships though. He said that if someone was to run it again, they shoudl just swap in a Motech system (or other aftermarket ECU).

I've not seen a bundle, but Jegs and Summit racing have main, rod, and head bolts.

Probably just remove the resistor pack, but I've never done it, and don't know for sure. The only way to be sure is to understand the stock ECU injector drive circuit, and then scope the outputs when driving the high Z injectors to make sure that they are opening all the way.

Todd was pretty anxious to get his hands on them (did you sent them yet?, did you send them yet?). He's going through them and setting them up for the new engine I'm building. Yes, we got quite a bit of stuff. I'll start another thread with the story.

I don't either, as I don't know sh*t about these carbs. All he said was that the venturis were removed, and they were bored to 50mm. Oh yea, then he said don't bother trying to use them on your 200HP L6 as they are way too much.

Avoid mechanical injection. You are building a street car, right? I'd go with triple ITBs and EFI. Port the manifold to match the bore of the ITB. That should be more than enough air flow for the application. The only reason I am going with Mikunis is because of vintage racing rules. I've got EFI and dual 50mm TBs on their now, and it runs great. Great throttle response.