New Buildup

[z-ya]

Starting to think more about the new motor buildup. I've built low compression 300WHP turbo motors, and mid compression (8.5:1) supercharged ones, now I'm thinking something different. I want the high RPM power of an NA motor, and the low end torque of a quick spooling turbo motor. Low boost, but fast spool-up is the key. Want to have great throttle response similar to NA motor. WHP goal of 300-350HP.

 

Hear is my plan, please comment:

 

L31 (LD28 crank, L24 rods, bored 3mm over)

9.0:1 CR (forged flat top KA24 pistons milled 0.6mm)

Metal gasket

Full port and polish P90 (stock height)

One of the turbo grinds out there for a camshaft (suggestions?)

Port match intake and exhaust manifolds

L28ET exhaust manifold

Intake manifold and throttle body(s) top secret

Ball bearing T04E/T3 with stage 3 turbine (other suggestions?).

Maybe add water injection (no intercooler)

~7psi boost

Programmable EFI of some sort

 

So yes, I could run an intercooler, but frankly, I don't want to look at it. I want it to look sparse and clean under the hood. No unnecessary plumbing. No bling! Lots of black krinckle powder coat.

 

All comments welcome.

[Tony D]

Define "High RPM" power peak at 7 to 7.5K? or higher?

 

If so, JeffP's current build is looking pretty good.

 

Get rid of the stroker and run super boosted L28, and make power to 8200 or thereabouts, just like an N/A. Just sie everything accordingly, and make your boost threshold before cam peak power area, and it will react like avery big N/A motor...

[z-ya]

I'm thinking 7K for max RPM. I know I can build a 20+ psi L28 and get over 400WHP. That's not what I'm shooting for. I like the low RPM power of a quick spooling L28 turbo (300ft-lbs at 2.5-3k RPM). I want it to push me back in the seat at low RPMs, and be real fast at the top end. I've go the stroker parts less the pistons. Either way I'm going forged, so the stroker isn't costing me anything, but should add more power on the top end at 7psi and no intercooling.

[cygnusx1]

Sounds like a nice goal. How are you going to resist increasing the boost?

 

You might want a smaller turbo, or two, with large wastegates to maximize the low end thrust and still breath at high revs. I am no cam specialist but you might need to use semi-N/A oriented cam to get your 7000-8000 rpm power. Use the small turbo(s) to make up for the weakness of the cam at low revs.

 

Interesting goal and tough without variable cam timing.

[Tony D]

I'm thinking 7K for max RPM. I know I can build a 20+ psi L28 and get over 400WHP.

 

When considering JeffP's car, cut your boost in half, and you get the last dyno pulls we did. 10-11psi, 400+ at 7000rpms...

 

This Friday, final numbers (Z31 ECU and Alternator Diodes Permitting) we will FINALLY finish the ECU mapping vand have full boost figures.

 

But yeah, on 80 to 110mph pulls, the car was showing over 400hp at 7000rpms. 8.5:1 CR, and the N/A portions of the map were showing well over 300 ft-lbs of torque. It's a very nice build from what I've witnessed thusfar. BTW, even though full on boost threshold is around 3400rpms, no matter where you are in the rpm range below that, you immediately get 3psi when you flog it---makes for that nice torque bump below boost threshold, and augments the 3.0L, as well as 8.5:1 CR performance of an N/A engine.

 

And if you are lugging or cruising below 3300rpm, when 3400 comes, hold on tight!

 

Of course Jeff says "It still feels a bit sluggish" below 15psi of boost...

 

Degrees, it's all a matter of degrees!

[z-ya]

Thanks Tony, 350WHP should be doable at 7psi then.

 

A question for JeffP (and I think I asked him this last time I was at the MSA show): why is he farting around with OEM ECUs, is he into pain or something? With all that he has into that motor, why not get a good aftermarket ECU like Electromotive, or WolfEMS? Why not a Megasquirt? Then get it on a Mustang or Dynapack dynometer and be done with it. Screwing around old OEM electronics is not how I like to spend my time. He should get himself a modern system in there to get the most out of his motor.

[Tony D]

He he he.... his first dyno run down at Jim Wolf was showing 381 Ft-Lbs at 8.39psi at 4500rpm....and that was when he sunk rings on five pistons because it started running lean at 5525rpm when the ECU went from single fire to twice a cycle firing of the injectors!

 

He has since surpassed that mark with the correct tuning of the fuel curve.

 

And to answer that question, yes, he is into pain. Matter of fact, I spent two hours last Friday running a Mustang dyno for him while he ran the map on the ECU again. We got RIIIIIIIGHT up to the section where he formerly was having problems and an alternator diode toasted, and melted the lo-temp solder out of the rectifier block stopping our dyno running for the day. And to be honest, the first 30-45 minutes of that was me learning how to run the thing the most efficient way to get the car up to load quick enough to do what we needed to do. Once we got a routine down, we were mapping four blocks on his ECU at a time. The interface he has for the fuel table is very much like a standalone setup, it allows reburning of the stock ECU in a similar fashion.

 

The problem Jeff is up against now is that there is a point two places on the stock Z31 box where the ECU rescales the map. The first one is relatively low load and low rpm---they use a lot of the OEM for off-idle drivability which is understandable from an emissions and customer satisfaction standpoint. The SECOND switching point is where it will make or break wether the stock Z31 ECU will be able to support the system to the full 600+ HP Jeff wants. I recently dug up an old photo I had taken of Steve Mitchell's Z31, and was shocked to find that Steve's dyno chart had the SAME DIP at 6300rpms that Jeff was experiencing in his setup. Since JeffP formerly made his 415 RWHP number at 5800rpm and 23psi, this ECU anomaly was not an issue. And we had never really discussed with Steve where he was making his 600+ from (730+ ft-lbs of torque!!!) From the dyno shot I had taken, it became clear that Steve's unit was well past horsepower peak, so the dip was not an issue. On JEFFP'S runs, though, he is peaking now at 7000-7300rpm, so that calculation comes right in an area where you don't want an ECU farting and deciding to rescale the map and think about what pulsewidth it should be sending out to the injectors!

 

Formerly this was evidenced by a quick spike in AFR to VERY lean (under boost---BAAAAD!), and then to a PIG RICH situation which took a few to recover from.

 

On our final pulls we were jumping to 12.8 and 13.0 AFR under boost. We were not detonating like before, but the jump was still there. Jeff had JUST put in some parameters to alter the fuel block there to see if it would compensate, and on that run the car started misfiring, though we didn't see the dip before we shut it down. When we shut it down to cool, Jeff added even MORE fuel into the block in an effort to turn the lean spike into a rich spike which would tell us if we could get through that portion of the map without the former problem...and when we started up again, all the AFR's were 1 point leaner than they were before....and Jeff Discovered he was no longer putting out 14.1VDC from his alternator.

 

DENIED!

 

So hopefully we can get contact with someone at the dyno place and show up there tomorrow and FIND OUT ONCE AND FOR ALL if the stock Z31 ECU will handle a 600+ HP L28.

 

He ALREADY has the standalone purchased if the blocks won't work, and he then will know the limitations of the Z31 Box which is the theory he is testing. It's a great bunch of information for people to know if they are planning on using the Z31 ECU. It can handle and make a GOB of horsepower, but to do it you will have to BOOST the hell out of it because at this point it doesn't look like it will handle it over 6200rpms due to that recalculation routine. The software he is using should become available soon, and it will make for a viable option for people who want to use junkyard parts to tune their vehicles similarly to a standalone. It will easily support 450HP...

 

Jeff considered the M30 Box, but I deviled him to the standalone route. ;^P

 

But yeah, he was making 381 Ft-Lbs at 8.39psi of boost at 4500rpm, so 350HP at 7psi should be easily doable. The dyno is irreplaceable BTW. Wheel speed preceeding his 'problem area blocks' are requiring a 13% grade and making passes from 80 to 110mph...kind of difficult to do on the street!

[z-ya]

The key to this build is the turbo, and camshaft selection. Suggestions welcome.

 

The Mustang and Dynapack dynos are awesome tuning tools. I like the fixed RPM feature for dialing in a new map.

 

Set the RPM to let say 3000, and the dyno will hold it there, no matter what you do to the throttle. With systems like MS and WolfEMS, you can tune in real time, so press on the throttle until you are steady on a load point for the RPM the dyno is holding, then make adjustments while watching the wide band display on the dyno computer. OK, that map point it done, on to the next one. Do that on the street!

 

You can dial in a completely new map in less than an hour if everything is functioning OK. After that do some pulls, make a few adjustments hear and there, and your done.