ShawnSmith

I look forward to being out of break-in-tune, up on new cams, and filling the job of a "reference" 6.5L intake dyno run

mark kibort

I know you guys have bounced back and forth with stock and larger injectors to solve rich problems and then that quirky -luckly result of using the 4" tube with the stock MAF insert which seemed to optimize AFR's. Mark said he is still using the stock ECU as well. what kind of not-top secret stuff have you "tuned" with, besides the fuel regulator?

mk

Hilton

Now you're just fishing for a bloody-minded argument about the definition of what constitutes "tuning".

Spend the time talking to someone on the phone who can help get your car sharktuned

ptuomov

If you are changing cams, would it be too much extra trouble to test the engine with the stock and the modified intake manifold?

ShawnSmith

My car is presently at 6.5L with mildly smoothed intake work. I do not have Greg's all-out effort, but it's not completely stock either.

We're planning to swap in the new cams, move up to 24 pound injectors, and maybe add spacers, then sharktune the resulting package. The resulting motor will not be an identical comparison to the 6.5L with the radically reground intake, but it will at least allow some kind of comparison.

I don't presently plan to have Greg spend days more effort grinding and welding on my intake, and there isn't another one in existence to bolt on for testing. Maybe if Greg makes wildly heroic numbers (and it'll be the torque which would interest me, not the peak hp), then I'll donate another 12 liters of blood at the red cross to fund a future upgrade.

ROG100

One last thing to try before I decide on the spacers or not.
We will try them on a stock car and dyno before and after.
By the way they look awesome on the car - bling factor is a plus.

mark kibort

Shawn,

what kind of head work and what cams do you plan on using?
Is the only mod going to be the intake being "very " honed out?

mk

mark kibort

Now lets get real. there is race tune and there is street tune and probably there is safe tune. You get our cars optimally tuned with even the shark tuner, and see what happens when the engine oil is 260f rather than when you are tuning at 180-200F. I dont know for sure, but I imagine things can change beyond what our 20 year old adaptive LH systems can handle.

Race tune. allow the car to start, run around the paddock, and optimze HP and torque from 3700rpm to 6600rpm. min knocking.

street tune. allow for easy strart, nice cold performance, hot performance, smooth acceleration across all rpm and loads, no pings, good fuel economy at cruise, etc.

Im not defeding my abiilty or lack of ability to get in the final stages of tune for my engine, but my primary concern is the motor safety with more hp vs the old stock engine. Since the shark tune only address fuel in most cases, and spark can be more dangerous as the engine heats up, im sure I could get some gains in some areas of the current HP curve. Is there 30hp for moving fuel mixtures around? I dont know. probably near 50 if we could play with fuel and spark and optimze, along with cam timing. All the possible combinations are the reasons tuning takes so much time and can be quite expensive.

Get me the best power out of what I have from 4500rpm to 6600rpm and I could care less about how it runs in any other area. (actually its not true, i kind of like the fact that my car runs and drives just like a stock 928 now) . Very smooth power, no dead spots and great fuel economy. (bad at the track though becuase it is so rich)

Bill and I were trying to tap in to the ECU but it has some quirks we need to get through before we can do a shark tune. When I get to the point were I can dedicate some time and money to it, Ill do my best to tune the darn thing!

As a race car, there are so many other things that are more important now. my suspension needs a total going over..etc. As it is, its still pretty quick around the track.

Thanks,

Mark

ShawnSmith

I am presently on a combination of GT intake and GTS exhaust cams - the exhausts will be swapped for Greg's yummilicious-reground-cams.

I have a stock intake to which Greg had applied his "standard" effort at smoothing various passages. Only Greg could tell you all the details which are different on his new no-holds-barred-max-out-every-nook-and-cranny-on-the-stock-intake effort, but as I understand it the changes are significant. I believe the other car is going with a black-bird-ish setup, whiile I have a bone stock looking S4 engine bay.

I believe my car and the other one have similar head work, which is extensive.

hacker-pschorr

It's no different than any other race car that spends hours on the dyno once the motor is broken in.

No offense Mark, you are not qualified to do this (neither am I). It's time to pay an expert before you grenade that very expensive engine.


Some of us do know, and we know for a fact your car is no where near this limit.

People are doing just that on a daily basis with race cars. I spent last evening at the dyno watching a T1 Corvette getting ready for this weekends NASA event. The hotter the engine got the more power it made.

mark kibort

Here is the before dyno with the fuel curve generated by the in-the -header wide band O2 sensor. Two dyno runs. one as we brought it to the dyno with fuel turned down a full turn on the regulators, and then still another .5 turn to lean it up a bit. notice the HP and torque dont change much at all even running at 11.5:1 . I turned it still another .5 turn yesterday, but after mounting the fuel pressure guage, i think we have run into the limit of the regulator, so the only way to lean it out will be with the 24lb injectors. thoughts?

Here are the original dynos before the spacer with the fuel curves. Notice the 1 hp gain going from 11:1 to 11.5 AFR. what do you think the gains would be if we got the fuel to 12.5:1 . What if optimal was to get near 14:1, would I want to set it there, knowing that the track conditions are grossly different? All things Im thinking of when looking at optimizing the HP of this engine. All things that most tuners take into account when tuning, I agree.


I just added the latest spacer dyno as the last dyno sheet, to have all 3 in one place

mark kibort

No offence taken.

Do you think im endager of hurting the engine based on what we see here?

I wonder what the limit of the set up is right now. If we were only to use fuel, what are the limits that "we know"? as far as I know there are not many stock head gt cam'ed 928s. Deveks had better cams and heads and only made alittle higher than mine is making at the start with a stock intake.
Andersons with the heads and cams made near 420wrhp , near what the similar set up Devek motor made. I think without some major head work, that the real limits are in the flow of the heads and intake.

Yes, many engines are tuned at the dyno and go through the super hot , unknowned area on the track. And, many engines dont last that long.

7 race seasons on my stock S4 engine at 335rwhp and looked perfect after disassembly. I think we have found the safe formula with the fuel range.
So, you tell me. What is the expected theoretical limit of the 6.5 liter with all the stock 928 components, ONLY changing fuel. (Because thats what we are talking about here)

It might be worth knocking down my injectors to a 24 lb'er r to start to see if i get any gains by gettting into the 12:5 AFR ranges.

So since we (you ) know what the limits are of a 6.4 liter engine with stock heads is, please let us all know what that limit is and what is done to acheive it!

mk

928SS

I wouldn't go to a smaller injector.

24's were ok till we installed the blackbird, windage tray, pan spacer, cleaned up the heads and used larger primary devek headers (1 3/4"). then we had to go to 42's cause the 24's were at 90% + and it was lean in a lot of spots even w/a RRFPR and nearly maxed out fuel pressure even w/a sharktuner.

once the 42's were in, we were able to run FP within injector limits, and used the sharktuner to dial it in across the board. picked up just under 40rwhp on greg's dyno w/all that done.

so if you plan on doing any other mods and tuning, I suspect you'll end up w/the 42's again anyway.

I've been thinking about messing w/the intake, but unless I see real gains that'll fly w/the smog nazies somehow, I'll hold off unless this becomes a dedicated track car.

I keep thinking a decent dry sump would pick up 10-20 rwhp and help longevity too... might be able to slip that by.... topic for another thread.

Bill Ball

As to Mark's engine and tuning -- we were foiled by the early protoype LH system that does not have the diagnostic connector wired. John Speake gave us what should be pretty simple wiring requirements. We just haven't had time to get together, do it and see if it works. Unless Mark has time during the weekdays, I'm booked until late May.

mark kibort

Thanks. Well, thats easier that way anyway! Did you mean 30lb'ers or really 42lb'ers? I have 30lb injectors now.

By the way, here is a plug I pulled last night after the dyno runs and some hyway bursts. keep in mind, these are the original plugs put in the stroker from the beginning. 10 race days later and a couple of thousand miles.

Hacker..... does this look like a sign of an engine that is going to blow?

mk

edit: By the way, andersons car has always made near what joe fans car makes. Joes DOESNT have the dry sump. in fact, fans has always made a little bit more and both have near the same stuff. If there was 20hp to be found there, anderson car was certainly ailing when it was making 410-420rwhp then. (as it has always had a dry sump system)