All parts are done,what power can I expect?

Post by **str8-6** » March 17th, 2015, 3:43 am

What can I get out of this new engine of mine? And will it stay in one piece?

89 Renix block 0.060 overbore with Speed Pro Hyper pistons,258 rods polished and weightmatched (0.7 grams diff on the big end,0.2 grams total) 1.9 grams diff on the piston/pin =2.1 grams diff on rod/piston/pin.

1973 258 crank (was 12/100 mm bent,but thats fixed now it's 2/100 mm off) balanced with the flexplate and harmonic damper FP= 0.45 grams off HD = 0.3 grams. crank 0.2 grams front and 0.8 in the back,close enough for a cheap engine...

7120 head ported by yours truly "looking at pic's and imagined airflow"= looks good according to those who knows what they are doing... first port job I've done in 25 years... stock valves and 3 angle seats head not ready yet,still has to do combustion chambers and seats,thinking of sinking the seats 0.010-0.020 to lower spring pressures a bit "100 lbs installed and 284.?? intake 295 exhaust" and then raise the roof of the combustion chambers to lower C/R to 10.4 "ish" intake runners ported more on "the big side" around the valve to promote swirl.

0.031 shaved from the deck and 0.007 from the head gives a 10.6 c/r and 0.55 quench,will work on swedish 98 octane fuel "I hope"

Lunati Vodoo [email protected] in [email protected] out 106 C/L 110 lobe sep. .527/.548 lift@valve "big" tube headers whit a full lenght 3 inch exhaust, ported Offenhauser intake and a Holley 600 carb rounds it up,will give it a 75 hp shot of nitrous "if need be" pistons should be good for a 100 shot so I will stay on the safe side...

Whaddayathink,I'm thinking around 300 hp at the flywheel,everything over that will be a bonus...

Post by **Cheromaniac** » March 17th, 2015, 12:03 pm

str8-6 wrote:Whaddayathink,I'm thinking around 300 hp at the flywheel,everything over that will be a bonus...

If you can get the engine dialed in correctly, 300hp at the flywheel is a realistic prospect. I ran a simulation of your combo on my desktop dyno.

Post by **str8-6** » March 17th, 2015, 4:24 pm

Thanks Dino!

That's what I been counting on,but there is a small difference: My headers are big tube according to the description in the manual for the Dyno Sim 5 program

The intake is a gutted out Dual-port so it's somewhere in between a dual and single plane intake leaning more to the singleplane then a dual,the plenum is opened up so the floor/divider for the secondary is all gone under the carb (open plenum) and also as far as I could reach into the channels from each end,thought of sawing it with a bandsaw and take the horisontal divider all out and divide it between the channels all the way to the plenum,but the no 3 and 4 would be way to short compared to the others and time is to short to get it done even with our swedish whinters...

I really wish that some company had made a tuned intake-manifold for our inlines.

Clifford has a "new" intake with dual weber 38's wich is as close You can get without going to Weber DCOE's,but as usually Cliffords stuff is way to costly for an underpaid Swedish busdriver...And with that intake You would have to go to a direct port nitrous system instead of the plate system I've got now "more money the wife thinks she can use for better things"

My next project will be building a tuned intake for 3 downdraft Weber 48's,it seems to me that it's easier to get even lenghts from the carbs to the head with downdrafts instead of side-draft 48's that will have very uneven lenght for the center carb compared to the outer one's

Post by **Russ Pottenger** » March 19th, 2015, 12:40 am

I'd strongly recommend Not sinking the valve seats.
It will have a negative affect on airflow.

If you're wanting to increase the installed valve spring height i'd suggest cutting the valve spring pocket
on the cylinder head.

Post by **SilverXJ** » March 19th, 2015, 4:26 am

str8-6 wrote:thinking of sinking the seats 0.010-0.020 to lower spring pressures a bit

I agree with Russ. Don't do it. It will hurt flow and throw the valve train geometry out of wack. You can fix the valve train, but not the flow.

Post by **str8-6** » March 19th, 2015, 8:50 am

Didn't think of that,I'm so stupid some times... got an idea that it would serve a double purpose : less valvespring-pressure AND bigger combustionchambers for lower compression,sometimes this brain of mine goes to fast for it's own good... Thank's guys for telling me BEFORE I got the time to grind away...

All parts are done,what power can I expect?

All parts are done,what power can I expect?

Re: All parts are done,what power can I expect?

Re: All parts are done,what power can I expect?

Re: All parts are done,what power can I expect?

Re: All parts are done,what power can I expect?

Re: All parts are done,what power can I expect?

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