its already onWhens it going on Ed?
coach said:With it being BB, it's going to be lower then a journal bearing. I would put it in the 3000 range, but if you ask Dusty Bradford...you will get your exact answer.
Is your motor stock stroke or a 249 stroker or bigger? This also plays into stall for the turbo. My 66 on a stock stroke needs a 3500 or so and with a stroker, it only needs a 3200. Add BB and it goes down another couple hundred RPM's. PTE has a recommended stall chart for each turbo too, but Dusty is the man!
Coach
Just eliminating the factory MAFS when over 500hp has a significant effect on spool
818GN said:Bison, can you explain how the factory MAF inhibits spool above 500hp?
I have a 6266 arriving Wednesday from Cal, and this statement peeked my interest.
The factory MAF flows terribly even with one screen out. It slows spool on all applications but it is worse the more mass flow the engine uses. Once you get over 500hp with it then remove it you will feel a big increase in spoolup and get a reduction in back pressure since you have raised the air pressure at the inlet of the compressor. It takes less ex energy to build mass flow if you start with close to standard pressure on the inlet. The stock MAF creates a huge vacuum at the inlet when you start making power. On the old 60-1 combo from 2 years ago it was limited by the factory MAF to about 25psi at sea level. Removing the MAF with the xfi install without adjusting the wastegate setting netted almost 35psi and it spooled nearly twice as fast.
we4Mateo said:Any tests of different MAFs? I know the stock ones were a choke, especially at your flow numbers but what about a true 3" LT1 or bigger LS style? Just curious.
818GN said:Bison, can you explain how the factory MAF inhibits spool above 500hp?
I have a 6266 arriving Wednesday from Cal, and this statement peeked my interest.
There is a lot of variation among "3200" converters, so you should measure the stall speed yourselves. (RPM at 0 psi, and 5 psi, as well as how it couples at the top end)
What kind of converters?
818GN said:6266's should arrive Wed/Thur, I am hoping.
Once, they are on, are we go out to a vacant area for tuning, I will post the RPM's at those points mentioned.
Tranny/Converter built and spec'd by 4C's out here in SoCal.
They specialize in Turbo Buick, Typhoon, and Syclone transmissions.
--------------------------------------------------------------------------------
What psi does the 6266 shine at? 25lbs? 28lbs?
My motor is forged/girdled w/ Champion irons, so I'm not too worried about turning it up.
It flows up to 78lvs/min with the right stuff. With iron heads and off the shelf cam it will take over 30psi to reach that flow. My stock stroke with a 6265 and gn1 ported heads hit that number at 28-29psi. I'd expect it to hit that with your parts around 32-33psi.
That's if there is nothing else holding it back like the MAF restriction, intercooler, or converter.
I did a dyno test with the 6265 about 8 months ago. I posted results in a thread. It was done at less than 3:1 PR on my stock stroke but the heads were really good. I was actually slightly over cammed for that turbo to make peak cylinder pressure when run all out. I'd likely use a 210-214* fast ramp lobe with 110-112*LS and advance it 2-4* depending on a few things. I had a custom 218 in it and it still worked like a champ but peaked a little later than I'd want trying to milk the most out of the turbo. Peaking at 5400 on a stock stroke with the compressor around 2.8:1 PR, 76-78lbs/min would be ideal. I made 696whp with mine@28-29psi then it was done. I went up over 30 and it blew hot air to the point my charge air at the plenum was up 60-70* over the best performance I got and that's with dual alky. So alot of heat. Another area that could show some gain with that compressor is the cover. The S cover is as big as they offer and it could likely pick up a little especially the way I ran it with more compressor cover. Even if it picked up 4-5lbs/min it would have let me get to about 725whp.