Streetable compression ratio?

[Sleeper]

I'm working on a 4.1 stroker motor, and ran into a problem with I discovered after the build, that the piston was 0.145 down in the hole, giving me a really low compression ratio. One of my options is to go with a longer rod 6.500 vs the 6.325. That will bring me up to close to .0045 clearance.
Using some different online calculators, I got a static compression ratio of 9.455, 9.5, 9.7 and 9.64 : 1, and dynamic ratios of 8.1, 8.77 : 1
Jeep Strokers • Dynamic\Static Compression Ratio Calculator
Compression Calculator by ZealAutowerks
United Engine & Machine Co. Incorporated
Compression Ratio Calculator

I'm wondering if these compression ratio's are too high for 94 oct pump gas street setup?

Here are my build specs, with proposed rod change:
4.1 block bored to 4.005
* Deck height of 9.5325
Stroke 3.625
Rod 6.500
Head CC 46
Piston Dish 33.5
Piston compression height 1.225
Head gasket thickness 0.039
Cam intake closing ATDC @0.050 lift 39 (215/220 roller)

Looks like I would have a deck clearance of 0.0045 with this setup
* This is from me measuring the piston in the hole depth of my assembled STD 4.1 short block with a dial indicator. The rotating assembly came from a Stage 1 block that had a deck height of 9.3878 and was 0 decked.

 

[bison]

Looks like you will be kicking ass with this one. I myself will run up to 9.5:1 for a street car. You won't be running more than 13-14psi without detonation on straight 93. With alky I wouldnt be afraid to run 21-22psi. You should be around 650whp@ 22psi. Otherwise I'd run 116 octane and up to 30psi depending on the cam used. I'd keep it under 650whp for longevity though unless you are using a stage block

 

[CGASTON]

You could also run E85. I have 10:1 in my car.

 

[Sleeper]

Looks like you will be kicking ass with this one. I myself will run up to 9.5:1 for a street car. You won't be running more than 13-14psi without detonation on straight 93. With alky I wouldnt be afraid to run 21-22psi. You should be around 650whp@ 22psi. Otherwise I'd run 116 octane and up to 30psi depending on the cam used. I'd keep it under 650whp for longevity though unless you are using a stage block

Thanks for the info. Greatly appreciated.

 

[bison]

You could also run E85. I have 10:1 in my car.

That's a great idea

 

[novaderrik]

You could also run E85. I have 10:1 in my car.

this is how i want to build a 4.1.. i'd use the factory heads with the best chamber (i think the 89 fwd heads like used in the TTA would work pretty well..) and try to do it with a reverse dome piston that mirrors the shape of the chamber instead of a dish. the higher static compression would limit total boost some, but it would be snappier in everyday driving and get better gas mileage. running E85 would make a combo like this doable.

 

[bison]

this is how i want to build a 4.1.. i'd use the factory heads with the best chamber (i think the 89 fwd heads like used in the TTA would work pretty well..) and try to do it with a reverse dome piston that mirrors the shape of the chamber instead of a dish. the higher static compression would limit total boost some, but it would be snappier in everyday driving and get better gas mileage. running E85 would make a combo like this doable.

Running a dome with a head that has 46-48cc displacement. Lol. Please post a vid when you mix this with some boost.

 

[Mike Licht]

By reverse dome he means dish, sounds like a great setup to me
Mike

 

[Nick Micale]

By reverse dome he means dish, sounds like a great setup to me
Mike

JE makes a piston like that, I just installed a set in an engine we are finishing.

 

[bison]

By reverse dome he means dish, sounds like a great setup to me
Mike

Got it. Id do everything i could to add some integrity to those heads on the intake side. They deflect with high cylinder pressure. Tom at Champion has a nice solution to this.

 

[novaderrik]

a reverse dome is just a dish that mirrors the shape of the combustion chamber.. so instead of a big hollowed out hole in the top of the piston, you've got all of the squishing and banging being done within the compustion chamber. about half of the top of the piston would be flat and give some quench area below the flat machined part of the combustion chamber.

 

[bison]

a reverse dome is just a dish that mirrors the shape of the combustion chamber.. so instead of a big hollowed out hole in the top of the piston, you've got all of the squishing and banging being done within the compustion chamber. about half of the top of the piston would be flat and give some quench area below the flat machined part of the combustion chamber.

Who would fund this kind of piston design for a buick v6? Its expensive for most as it is running a forged piston based of a Chevy design and thrown into these engines. I dont think many will have it in them to fork over the $ for a project like this. You could build a 1000hp v6 for the amount it will cost. Someone will be paying huge for the initial setup and then need to have the $ ready to make a run of them.

 

[Mike Licht]

Diamond already has this piston, I took a head there and they mapped the chamber, that is why their dish is n ot a round bowl like the others, who funded it? Me
Mike

 

[jasjamz]

Diamond already has this piston, I took a head there and they mapped the chamber, that is why their dish is n ot a round bowl like the others, who funded it? Me
Mike

Like these?

 

[machinegun]

mickey mouse ears and they work great

 

[bison]

Thanks Mike. Hopefully htey wont sell it to anyone unless they go through you.

 

[Mike Licht]

Thanks Mike. Hopefully htey wont sell it to anyone unless they go through you.

That stuff rarely works out, I have a couple part nummbers that are mine but I am happy with our arraingment.
Mike

 

[m233roller]

Ole Mikey is always athinkin and we are damn lucky to have him around in our Buick world. Hi Mikey.!!!!

 

[vic86gn]

Ole Mikey is always athinkin and we are damn lucky to have him around in our Buick world. Hi Mikey.!!!!

+1........

 

[KL Mallender]

I commend Mike for investing his time and effort to this concern, many do not fully realise the importance of valve-piston clearence needed during the overlap period.
Fwiw, many do not (or fail to recognise) what "Quench area" truely represents,....it ain't mixture "motion" and is much more important than 95 % might care to know.
Good luck,

Kevin.