B2 Motorsports - Mat Twiehaus 427SBF Build

[Clois Harlan]

I have gone back and looked at all the parts and effort put into this build and I am comfortable guessing maybe 750 fwhp. Given that much power Mario Andretti should be worried should he happen to show up at a Run N Gun event!

[ERA Chas]

Mat-you'll read this after the dyno but here's a thought.
Mount the tank in the passenger footwell, maybe with some chassis tubes around it and sheet metal protection around it. Eliminates the long line runs...

[AL427SBF]

Dyno day, very interested to see what the numbers come in at. Too lazy to look, but has Brent posted the the compression ratio? Guessing for pump gas no more than 10.5:1?

[Jerry Clayton]

Brent---you don't have much control over the amount of vacume you will pull with this set up---it will pump so much according to the pump sizes and speed(rpm/belt drive ratio)that you choose and be countered by amount of leakdown /blowby and volume the pressure pump puts back into the crankcase----your relief valve ??????????will hopefully prevent the loss of intake gaskets with the push/pull/push pulses in the ports

[blykins]

Originally Posted by Jerry Clayton

Brent---you don't have much control over the amount of vacume you will pull with this set up---it will pump so much according to the pump sizes and speed(rpm/belt drive ratio)that you choose and be countered by amount of leakdown /blowby and volume the pressure pump puts back into the crankcase----your relief valve ??????????will hopefully prevent the loss of intake gaskets with the push/pull/push pulses in the ports

Jerry, you nailed it buddy. We were pulling about 3-4 inches of vacuum today without any change when we were playing with the regulator. I used a teflon rear main seal and tried to seal the engine up as best as I could on the other gaskets. I honestly just don't think the dry sump pump was big enough to pull the big amounts of vacuum.

It's kinda hard for a street engine that will be raced part of the time. Of course the vac part of the pump probably could have been more worthwhile with some pretty low tension rings, but I really didn't wanna go there if Mat's going to be driving it on the street a lot of the time. This engine is a balance of street car/race car. Sometimes it's hard to draw lines.

Well, for the results...

573hp @ 6400, 562 lb-ft @ 4800.

It ran very well. No issues, no leaks, just a good strong engine. I think the horsepower peak is a testament to the cylinder heads as the cam is just 240° @ .050".

AL427SBF, the compression ratio was around 10.3:1. I can routinely get away with about 11:1 SCR around here with 93 octane, but when I send engines out, I want to be sure that they will run on the gas that's available where the customer is. A lot of cities only have 91 octane, etc.

This thing needed about 10 more degrees duration on a solid roller cam and it would have been real fun.

I'll post the dyno sheet later on. I got back, trying to beat the rain, then cleaned the engine for Mat and taped everything up. I'm pooped. I also had a customer who was rear wheel dyno'ing a 408 LS2 engine this morning. Needless to say, my nerves are shot....hahaha That one made 501hp at the tires @ 6000 rpm. Not too shabby.

[ERA Chas]

Originally Posted by ERA Chas

OK-I'm gonna show my ass and say, 1.35 HP per CI.
570-575 HP @ 6200
540 LBFT @ 4900.

Hey Brent, why did you reprint my quote as results??
---NO WAIT-I was right on! OK, you out-torqued me a tiny bit...
Well kudos to you-you built the danged thing. And nobody wore shrapnel home from the dyno.
Always a good day.

[AL427SBF]

Thanks for the CR Brent, that's about where I'm at with the Gessford motor, one day I'll post what I get, similar motor.

[PLDRIVE]

Nice Job Brent

Brent when u have time post some info on Daileys pump. How many stages, and what size are the stages? What was the pulley ratio. I Have a Aviaid S2 5 stage and was hoping to pull 12 inches. Plan on getting it up and running in the next couple of weeks.


Ok i am still at a loss on what some of u are saying regarding over pressuring the crankcase? I do not understand how this can happen if it is plumbed the way i was told to ( suction side = -16 from pump to oil tank, oil tank is then vented to small vent tank). Now with that said, if u blow a piston, will the pressure not go through the suction side of the pump travel travel through the oil tank and vent out of the vent tank??? What am i missing?? I have never had a dry sump system, so i want to make sure i do not miss anything.


Mark