BC

todd now has over 800 (I think at the wheels) with a stock block, stock heads, stock cams, and an Autronic EFI. The pistons have reduced the compression with 951 pistons which make it more like 7.5:1.

He does this on pump, 93 octane gas.

Mine are regular 928 pistons, but with ethanol, I don't get pre-ignition or knock. So yes, those are my goals. The first one a realistic, and the second a stretch goal.

I have done nearly everything I can do to the stock block to make sure that, without changing its original structure, it stays together - girdle, proper cranl scraping, pan spacer, arp head studs, cometic gasket.

I want to make sure the only reason anything would blow up is because the structure couldn't handle it, and that will probably not happen before I stop increasing the boost.

Detonation, according to Corky Bell, increases the total combustion pressure to 10 times normal That means that if you detonate at 500hp, that pressure in the chamber would go to what it would see at 5000hp for the total engine. Its not built for that.

But I think it would stay together under controlled combustion up to 1200 crank or so.

BC

remember that the rich mixture for E85 can go down to 6:1 afr. Todd is doing 850 or so on I think 82lb injectors.

John Speake

Hello Ryan,
You don't need different maps. When you increase the boost you just start using (premapped) areas of the mapping (higher load values) than at lower boost. JK is using a cockpit adjustable boost control with his TT setup with no issues, whatever the selected boost level.

So no chip switching involved.

Use the other set of maps as a get you home on 93 setting, easily selected by switching the code plug from non-cat (E85) to cat (93).

123quattro

I was taking that into account when I came up with those numbers. My Audi is making 500 hp with 5 60# injectors on race gas.

BC

Well good then. It seems as though you have helped me decide that the 72s I bought will not be big enough even with more fuel pressure.

Pictures of my fuel rails were in the other thread I started,





And all fuel lines and transfers are at least -10 AN. From and to the tank will be all the same size.

Its maybe a bit over kill. But I can use it in other 928 bodies no matter what happens to this one. And its fun.

BC

http://www.change2e85.com/servlet/Page?template=Myths

blown 87

I think that with your approach, IE, trying to do everything right.
You just may reach your goals.

Making those kinds of power levels are not for the weak of heart, or wallet for that matter.

Interesting thread, for sure.

dprantl

That site sells a kit to convert any engine to run on E85. So this will also work for the 928, as the site says?

Dan
'91 928GT S/C
'86 928S 5-spd w/LSD *sale pending*

BC

Honestly those kits are WAY over priced. All the do is take the voltage from the computer, and lengthen the signal a bit - usually 15-20%.

Thats all that I can see them being able to do. Because baring other requirements with rubber, pumps, etc, all you need is more fuel.

The one issue is that the 02 sensor will show a "lean" condition at normal mapping places - so it will try to add more. Usually correction factors are limited - maybe 20% more can be added stock.

02 sensors read oxygen. There is more 0xygen in the exhaust of E85 because more was in there when it was fuel. Thats why a stoich for Ethanol is around 9:1 or so.

You could simply (this is my opinion) run a 928 with a rich setting (pig rich) and be done with it if there is enough duty cycle possible on the injectors.

Crap, with the early cars with NO 02 sensors, all you would need to do is buy an adjustable FPR (good for alcohols) and jack it up. And advance timing. More power on fuel from the pump.

For the CIS people, depending on corrosion, you would just adjust it to pig rich.

Technically, to get the full benefits, you need high compression, more fuel and more timing.

BC

With your 91 with the boost (which is perfect), you could jack that boost up with as small a pulley as you can run and just increase fuel pressure on larger injectors and have at it. You already have everything you need - BOOST!

People reading this may say to themselves "no way" but really - because there is pretty much no detonation with proper tuning on E85 on boost - how hight do you want to go? 16psi? 20psi? 25? Because as long as you run it pretty rich (7-9:1) and don't go crazy with timing (but run more than with gas) it won't pre-ignite.

You would blow a gear or shaft on the trans before you blew that engine up. Maybe a headgasket from the total pressure, but not from detonation.

Lizard928

Brendan, what fuel pump(s) are you running, or going to be running with the system.

And damnit Ryan, you just had to start this thread didnt you. Now I am considering E85, though I will probably have to order it, as I dont know of any stations in canada the make it.

or of course brew my own.

RyanPerrella

Honestly i think the brewing your own would be a PITA. who wants to have that much combustible gas in your garage anyway.

RyanPerrella

Great to know John,

Can i assume that the MAF knows when there is more air coming in (higher boost) and it adjusts on its own. How does it adjust, by lengthening the injector pulse time?

Would you sharktune the car on the high setting or low or in the middle somewhere? Or do i really not understand in which case tell me to read the Bosch Fuel Injection and Engine Management handbook which is right next to my bed, yet ive never read. I assume that after having read the book i will be much better with the Shark Tuner when i end up getting one around the time that the TT setup that i come up with is ready.

BC

Weldon has some great pumps - I will be using those. -10 holes, and they also have a -10 FPR that is also made for methanol and nitro - hence no issue with ethanol.

TECHNICALLY, because of the need for so much fuel, I have to get a REALLY big pump.

RyanPerrella

Brendan, did you say your pump was $1400?