What effect do displacement and supercharging have on runner length? I currently have a Nazman Psr on my 4.6 and I'm going with a 323 bb/stroker. I'm considering to swap a FR500 intake in place of the psr but I didn't know if it would have the same high rpm only benefit or if the increase in cubes and pressure would move the usable rpm down.
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The relationship between cubic inches, boost and runner length.
- Thread starter omj
- Start date
I have a Fr500 intake on a 323 bb/stroker. All I did was modify the top plate to accept a cobra R SVO throttle body and delete the tumble flaps. I didn't make it a dedicated short runner longs are still in place.What effect do displacement and supercharging have on runner length? I currently have a Nazman Psr on my 4.6 and I'm going with a 323 bb/stroker. I'm considering to swap a FR500 intake in place of the psr but I didn't know if it would have the same high rpm only benefit or if the increase in cubes and pressure would move the usable rpm down.
Car made 460hp and 386tq to the wheels. It pulls power to about 7500rpm just shy. So the engine is making 530/445 ish depending on drivetrain loss.
If I want to make more power I need to widen the cams a little and throw in a little more duration like 250+ish. I'm pretty tight for a modular with a 109LSA and a 105 CL so it's in the 20's for overlap sounds good and performs good and peaks early for a street car. First modular I ever put together so I'm happy with it.
TQ comes in at 300+ from like 2600 and carries it out to about 7200-7300 peaking at 5250 as usual so its pretty flat which is nice. HP is 300+ from about 4200 till I stopped the pull at 7500rpm. The HP is 450+from 6500 to 7300 then just dips below at 7500 ish. Peak is right around 7K where the cams should be the way its set up. Even without the flaps you can see the air naturally flow from the long and shorts it gets this HP TQ dip at 4500 rpm, its a weird dyno graph looks like two TQ peaks and two HP peaks its pretty cool you can feel it and hear it, its like a natural v-tec lol.
If I hack the intake up (cant do it) and get some bigger duration cams with a little wider LSA it will push the powerband probably to 8K making some more maybe 500-530rwhp. I kept it lower, wanted the peak at 7K street car so I figured I could pull it out to 7500 ish which it does. I originally was expecting 475-500rwhp but it came close.....
Depends on the cams but the PSR will make more low to low mid end. But the 323 helps with it and makes some more in the mid upper with the fr500. Depends where you want the engine to play. When I had the factory 3.27 gears the thing would pull for ever texas mile car lol. The 4.30's with the 28inch are happy with this setup and makes the RPM usable on the street. Ton of cam surge with the 3.27's lugging around even the 4.30's do it. The FR500 and 323 are matched well like I said this is a untouched intake. A 4.6L and fr500 would need 8500+rpm to make this.
Now I'm putting a blower on it so will see.
Hope this helps.
Did you ever dyno your motor with a stock intake?
No I never did, I had to modify the Idle air valve location the throttle linkage and I switched to a Wide oval SVO cobra R throttle body so I never wanted to undo all this. I know if I did I would've made a little more down low and maybe a higher peak TQ. But I'm never really below 4000 especially with the 4:30s so its really no loss.
I've talked to a few other people about the NA stuff. Some have told me to widen the cams and it would allow more power to be built in the upper RPM's. I spin it out to 7300-7500 now so I really didn't want to go any higher at this point. I was originally shooting for 500rwhp NA but it is what it is.
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