Streetability mods

General engine tech -- Drag Racing to Circle Track

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F-BIRD'88
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Re: Streetability mods

Post by F-BIRD'88 »

If the piston is high quality and the piston deck is thick enough it is possible but not cheap or easy to custom macine a dish in the piston top. But don't bet on it.
It also changes the piston weight. Effects balance.
RevTheory
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Re: Streetability mods

Post by RevTheory »

Dude- the customer doesn't want to pull the heads.

Water/meth sounds like something worth looking into.
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Re: Streetability mods

Post by Brian P »

Water/meth adds a bunch more failure points to the FMEA. There's no free lunch.
F-BIRD'88
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Re: Streetability mods

Post by F-BIRD'88 »

RevTheory wrote: Sat Apr 20, 2019 5:00 pm Dude- the customer doesn't want to pull the heads.

Water/meth sounds like something worth looking into.
Dude, nobody " wants to pull the heads "
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Re: Streetability mods

Post by PRH »

Longer, slower, wider camshaft.

Slow the advance curve.

If that’s doesn’t do it, put some thicker head gaskets on it.

Or visa-versa.

I just had a 360 on the dyno last week.......granted, it made way way less tq/ci than your build, and a bit less hp/ci....... but with 9.85cr, open chamber heads and 93 gas....... it never made a peep.
Somewhat handy with a die grinder.
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Re: Streetability mods

Post by groberts101 »

PRH wrote: Sat Apr 20, 2019 6:38 pm Longer, slower, wider camshaft.

Slow the advance curve.

If that’s doesn’t do it, put some thicker head gaskets on it.

Or visa-versa.

I just had a 360 on the dyno last week.......granted, it made way way less tq/ci than your build, and a bit less hp/ci....... but with 9.85cr, open chamber heads and 93 gas....... it never made a peep.
This. Cam change to bleed off some compression is pretty easy and cheap to do compared to all the above. Depending on his current fueling configuration, E85 conversion would likely be far better and easier to do above all else. E85 is cheap and probably make a bit more torque as well.
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Re: Streetability mods

Post by fdicrasto »

The MSD distributor does make tailoring the advance curve and amount of centrifugal advance easy. Coupled with less total advance, I wonder if along with either the av gas or Delta Sonic high octane pump gas, that this could make this combo ok for limited street use. I will be heading up to Rochester in late June and possibly get him to pull the heads and go with a thicker head gasket also but not sure if he will go for it. I wish he had contacted me sooner.
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Re: Streetability mods

Post by ClassAct »

fdicrasto wrote: Sat Apr 20, 2019 7:49 pm The MSD distributor does make tailoring the advance curve and amount of centrifugal advance easy. Coupled with less total advance, I wonder if along with either the av gas or Delta Sonic high octane pump gas, that this could make this combo ok for limited street use. I will be heading up to Rochester in late June and possibly get him to pull the heads and go with a thicker head gasket also but not sure if he will go for it. I wish he had contacted me sooner.

I run a measured 11.08:1 on iron heads and run it on pump gas with 35 total. I'm not sure on the cam but it sounds like it came off the shelf. With the correct cam you can make that power on pump gas. Tell him to get a different cam.
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Re: Streetability mods

Post by Orr89rocz »

E85!!! It is in new york, but need to know customer location exactly to find stations. That be the best option right night. Or order e98 barrels and mix that with your pump gas as long as it comes out e50 or better it will work
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Re: Streetability mods

Post by hysteric »

Where does it ping? Bottom, mid range or top end?

What does your advance curve look like?

Maybe you could just retard the cam a bit to bleed off cylinder pressure to see if that helps.
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Re: Streetability mods

Post by F-BIRD'88 »

If all it took was a big cam no race cars would need race gas. This is bs.
GARY C
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Re: Streetability mods

Post by GARY C »

One thing that no one ever factors in to these discussions is... How much fuel will you use based on your engine theory? Is using "more" cheap fuel better than using "less" higher priced fuel?

In theory you can run a 12.1 engine on regular pump gas at normal cruise and overcome knock with water meth injection while also producing a much stronger and broader power band... So should one just choose to reduce compression and power so they can run cheap gas?

Reducing compression to run cheaper fuel also reduces power and efficiency thereby hurting MPG, like wise trying to run higher compression with a cheaper fuel like E85 also reduces MPG thereby making you run more cheap fuel.

Has anyone here ever tried to build an actual efficient high compression "street" engine that would require something along the lines of a $6 or $7.00 105 octane fuel and the actually tested the mileage capability?

Not a big cam, big convertor, 4.56 gear race car on the street but an actual street build.
Please Note!
THE ABOVE POST IN NO WAY REFLECTS THE VIEWS OF SPEED TALK OR IT'S MEMBERS AND SHOULD BE VIEWED AS ENTERTAINMENT ONLY...Thanks, The Management!
BigBro74
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Re: Streetability mods

Post by BigBro74 »

E85 works so well at that compression- it would be a shame not to just fit the fuel system for that fuel. Problem solved.
GARY C
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Re: Streetability mods

Post by GARY C »

BigBro74 wrote: Sat Apr 20, 2019 10:09 pm E85 works so well at that compression- it would be a shame not to just fit the fuel system for that fuel. Problem solved.
How much more e85 would be required to produce the same power figures? Most inf I have seen says that E85 reduces MPG by 30+%?
Please Note!
THE ABOVE POST IN NO WAY REFLECTS THE VIEWS OF SPEED TALK OR IT'S MEMBERS AND SHOULD BE VIEWED AS ENTERTAINMENT ONLY...Thanks, The Management!
Brian P
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Re: Streetability mods

Post by Brian P »

GARY C wrote: Sat Apr 20, 2019 9:16 pmHas anyone here ever tried to build an actual efficient high compression "street" engine that would require something along the lines of a $6 or $7.00 105 octane fuel and the actually tested the mileage capability?

Not a big cam, big convertor, 4.56 gear race car on the street but an actual street build.
The mainstream auto manufacturers ... except without the need for super high octane fuel; the detonation is controlled by other means.

Mazda Skyactiv - 13:1 compression. Direct-injection without turbocharging.
Toyota "Dynamic Force" (current Camry and others, 4 cylinder engine) - 13:1 compression. Direct- and port-injection (blended). No turbocharging.
Pentastar Upgrade (Jeep Grand Cherokee, not sure if it has made it to other models yet) - 11.3:1 and without direct-injection. No turbocharging.

A pretty common theme is designing the porting to encourage strong tumble motion with the objective of eventually giving fast combustion, and *not* using turbocharging - so that the compression ratio can be kept high.
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