roller lifters with 2.8

[veekuusi]

If your air/fuel stayed between 12:1 and 13:1 from the bottom to the top of the range then that is pretty damn good. How much did you mess with the timing? How much advance do you have at 3000+RPM? Before you hack your intake all apart maybe just cut the one wall where the carbs are mounted and increase the size of the plenum and weld it back on.

Max advance is 30 degrees.
It has little or no affection to hp what the WOT timing is.
It maybe so that when other things are not perfect (in this case runner lenghts, plenum etc...),
it affects so.

You are right, I am not going to hack the intake apart, I just modify the upper part of it.
I mean ,shorten the runners and maybe make the plenum a bit bigger.

The runner lenghts with different carbs:

4 bbl Holley 6-7"
3 bbl PMO 6"
2 x 2 bbl Weber 13"
with those applications above , the power was about 150-166 kW

And with 3 bbl PMO carb with the 3" extension ( together 9"), the power was 186 kW (254 hp back wheels), the best so far.
With this combination, the exhaust temperatures were over 100 degrees celsius different from bank to bank (over 212 F).
It means the other bank did run lean and the other rich.

So, 9 inch may be the best runner lenght .
And the exhaust temperatures are the same with 2 x Weber application .

[geoffinbc]

If your air/fuel stayed between 12:1 and 13:1 from the bottom to the top of the range then that is pretty damn good. How much did you mess with the timing? How much advance do you have at 3000+RPM? Before you hack your intake all apart maybe just cut the one wall where the carbs are mounted and increase the size of the plenum and weld it back on.

[1988GTU]

How would you feed fuel? Those ITB are tall, & any plenum added would make it much taller. Are you able to modify the hood to accommodate for such without penalty?

[davida1_hiwaay_net]

No detonation sensor , but the dyno guy has special ear blugs connected to the motor.....

Wow. Just wow. That's a lost art, for sure. Out of curiousity I connected a detonation sensor to a tape recorder once. It is basically a piezo microphone. I could hear the engine running, but for sure it takes years of experience to know what to listen for. I do not doubt your engineer's abilities, but I don't see how he does it. It's going to be tough to react as quickly as an ECM can. It can pull timing and cut the boost off in an instant before you even know anything happened.

But there has been no problem what so ever with the detonation with this engine.

That's good tuning on your part!

[veekuusi]

I think you should go back to the single Holley 390 intake. Clean up the inside welds with a die grinder and try adding carb spacers to see what it likes.

If you still want to build another intake, maybe a variation on the single carb but try building a dual plane like the Edelbrock Performer RPM.

Can you run fuel injection ?(I forget) I bet a ported 3100/3400 lower intake, 3500 plenum and a 62mm throttle body would do really well. Plus it should clear your hood.

It is possible to run fuel injection , but that would put me to another class ( I am now in "roadsport B class" and with a 2.8 motor fuel injected would put
me to "roadsport A class). That is "big guys" class , to race to win takes some 300-350 hp in that category.

I wonder if this TCE ITB is still for sale:
http://60degreev6.com/forum/showthre...ck-up-for-sale!!!

[veekuusi]

Those plugs look really good.

Do you have a detonation sensor?

No detonation sensor , but the dyno guy has special ear blugs connected to the motor by a hose,
so he can hear the possible detonation while running the motor.
But there has been no problem what so ever with the detonation with this engine.

[davida1_hiwaay_net]

Those plugs look really good.

Do you have a detonation sensor?

[veekuusi]

It took the first hour in the dyno to get the lambda readings allright.
Wideband lambdas were used in both collectors.
The lambda was 12-13, so the air/fuel ratio is OK.
Emulsio tube F11
Main jet 220
Air corrector 125
Chokes 36 mm





Brand new spark plugs were installed to the motor before dyno.
Now they look like this.Picture is from drivers side of the motor.



And one picture from the cockpit.
I put an extra warning light for the oil pressure.
Right in front of the driver,upside the steering wheel.
Now it is impossible not to see it.

[Superdave]

I think you should go back to the single Holley 390 intake. Clean up the inside welds with a die grinder and try adding carb spacers to see what it likes.

If you still want to build another intake, maybe a variation on the single carb but try building a dual plane like the Edelbrock Performer RPM.

Can you run fuel injection ?(I forget) I bet a ported 3100/3400 lower intake, 3500 plenum and a 62mm throttle body would do really well. Plus it should clear your hood.

[SappySE107]

I know that some guys on the TGP forum figured out that roller rockers and pushrods from a 94/95 3100 fit and work in a 3.1. It's only a gain of 2-3hp but it's something. I can't imagine it wouldn't work in a 2.8mpfi engine as well.


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Its already roller cause its not a 2.8 MPFI. They weren't roller rockers either. They are ball fulcrum still but 1.6 vs 1.52 ratio. Thats where the gains come from in that situation. Its nothing that helps in this discussion though.

[Bnet_Travelor]

I know that some guys on the TGP forum figured out that roller rockers and pushrods from a 94/95 3100 fit and work in a 3.1. It's only a gain of 2-3hp but it's something. I can't imagine it wouldn't work in a 2.8mpfi engine as well.


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[geoffinbc]

Do you have an air/fuel ratio report? Or did I miss that on the paper? Just by visually looking and comparing other intakes I have seen on race motors I would agree that the runners are long and the plenum seems very small.

[Purple pit]

Really thought the torque would be higher. So what RPM are you shooting for?

[1988GTU]

How were your spark plugs looking after each pull/change?

[veekuusi]

Yesterday was the dyno day.
I must say , I am disappointed to the results.
166 kw = 227 hp 6940 rpm
250 Nm = 184 lb ft 3830 rpm
That numbers are from back wheels.
It it something like 250 hp from engine (this dyno can not calculate the power loss).
So nothing changed, same numbers than earlier, as with the 3 bbl and the 4 bbl carb.

Maximum hp came now 1000 earlier than ever , 7000 rpm.
And the max torque came also as early as 3830 rpm.

Best thing to notice was that the exhaust temperatures were the same with all cylinders,
so the middle ones do not suffer .
But the temperatures were only max 600 celsius ( 1112 fahrenheit), that is not much.
That tells that something is wrong in the 7000 rpm area.

"The garden hose" trick did not turn out as good as I expected.
We put the hoses every possible way.
From left to right ,and across .
Nothing changed.
At least the hp numbers did not change, only alteration was that the max torque shifted 500-1000 rpm upward
with the hose application.

The final conclusion was that the intake runners are now too long.
The engine "tunes" too early.
And perhaps the plenum is a bit too small.
Or what do you guys think?