Bob@BruteSpeed

iTrader: (16)

No, two totally different blowers. Thanks. Bob

Tirefire

iTrader: (1)

Hey Bob I read the thread on the new F1a my question is my compression is 9.5 and is sluggish. Would the new head unit affect me in a bad way down low? Is it same impellar speed? Sorry for all the questions. Thanks

Bob@BruteSpeed

iTrader: (16)

For your elevation you could indeed stand to have a little more compression. Have you experimented with adding a little timing to it? The new head unit would take away a little of the low end, as will any head unit larger than your current F-1A. It does have the same 5.40/1 gear ratio, and same 74,000 impeller speed. Questions are never a problem, Andy. Bob

algws6

iTrader: (3)

Bob, another thing I told Andy to consider is our DA rarely gets below 6000'. I also told him to run straight MS109 and bump the timing. FWIW on my 346 with my novi 2200 spinning to the max I see around 17-18 pounds.

Bob@BruteSpeed

iTrader: (16)

DA of 6000, that really sucks the life out of an engine!!! More timing would definitely help. Good info, thanks! Bob

Tirefire

iTrader: (1)

Thanks for all the help guys! Ill try this combo at the track and add some ms109 and some timing like Al said to see what it will get me.

Bob@BruteSpeed

iTrader: (16)

You're welcome, Andy. Let us know how it does. Bob

Monte4ever

iTrader: (2)

Anything new to report?

JoeNova

Wait, you maxed out 80 lb injectors and had to go bigger? But are only trapping 130? The last time I seen 80s maxed, traps were 150-155 mph @ 3600 lbs. Check your fuel pressure.

You've got a major issue somewhere. Throwing handfuls of money at it isn't the answer.

Bob@BruteSpeed

iTrader: (16)

Keep in mind Andy is at high elevation, which changes everything. Bob

algws6

iTrader: (3)

i agree. we have the same injectors but im on e85 and my duty cycle on the same night was 68%. i trapped 144 that night and run a base pressure of 60psi. i do have twin 15 meth nozzles but i still think something is up.

JoeNova

You're absolutely right, but in the opposite.

Altitude forces you to use less duty cycle because you aren't moving as much air and therefore less fuel.

80 lb injectors at a 58 PSI base pressure (boost referenced) are good for 1000+ flywheel HP. At 70-76 PSI base pressure you could make close to that on E85.

80 lb injectors supplemented with Meth are capable of 4 digits to the wheels. The fact that he is maxing them out at that high of an altitude and trapping 130 says he has a major issue in his tune or his fuel pressure is down dramatically. I've trapped mid 140s on 60 lb injectors and meth injection.

I'm almost starting to think one injector isn't firing, forcing him to run the others rich just to hit target AFRs and thats why his duty cycle is so high.

The Alchemist

iTrader: (19)

Maybe he's on the stock regulator, so it's not raising fuel pressure, so it compensates with leaving the injector firing longer, hence the higher IDC's. I know that's my issue. I need to put in a boost referenced regulator.

JoeNova

He said that he is on a boost referenced regulator. So unless his base pressure is 40 PSI, that's not the issue.

I'd almost be willing to bet he's running on 7 cylinders. He's using tons of injector, and only trapping 130. One of them isn't likely firing. Since he has since upgraded injectors, its probably a harness issue and needs to be tested.