[Curious George]

Here is my chassis dyno sheet from 8psi. First off, how will adding more boost affect the RPM range of power curve? Will it raise or lower peak HP RPM or simply increase HP at same RPM? Second, what affect will increasing headflow have? Third, How about longer duration camshaft? And finally, what RPM would I want to cross the finish line with using the above dyno sheet? Trying to get a handle on any changes I may wish to make for next year. Thanks in advance.

[BruceWilkie]

IMO your kind of showing your VE curve. Camshaft and headflow both influence that. Open the valves longer, higher or both allows less restriction to flow thus at same boost levels more mass flow = more power and usually at higher rpm depending on the cams influence on the VE curve.

Headflow pretty much the same.

The turbo has to meet the new flow requirements and stay in efficient range. yours should be good for a bit lol.

None of this is linear due to how the compressor flow "crosses the map" . Id test more to see what more boost does for you 1st. Probably consider head flow improvements before cam change unless its really way off. Generally boosted motors follow NA cam characteristics as long as overlap is modest. Typically peak torque comes in a bit sooner and holds HP a bit later.

[Curious George]

Thanks Bruce. I wish I was more informed when I dyno'd but setup was new and wasn't aware of all the questions I'd have down the road, lol. Trying to determine if gear, converter, and/or cam change is in order, but you're probably right about more dyno testing first.

[v869tr6]

My chassis dyno results show that with increased boost the peck HP number moves up maybe 200-300rpm. talking 18psi to 25psi but the change at the wheels was only about 70 hp
At below say, 1500 hp I don't see a 280cfm port as a issue at all.
Maybe Tom has a chart with the area of a intake valve open vs total area of a port.
Plus the valve is at full open only a very short time.

Make sure you don't go lean and turn the boost up!
No comparison between 13 psi and 18-20psi

[charlie66]

I think it will raise the power level all the way up the curve . Will start out almost the same around 300 rpm then start really changing at 5250 rpm where you will see the most gains there after 5250. At least that's the way it went for my 4 cylinder. 34 psi was 35 hp more then 30 psi . 40 psi was 25 hp more the 34 psi. But at 40 psi the turbo was getting very inefficient so it started falling off. Haven't had it back for more testing since the new turbo change , but I can tell it will well out perform the old turbo. The New one wants to just grenade the motor.. So I have to be very carful not to get carried away .. So adding more boost does change the curve if you ask me. As for the peak all I can say to that is mine was on the up till it hit the limiter which was set the same for all pulls on all different levels 30- 34- 38- 40 psi.

Increasing head flow imo would relieve intake heat at the same boost level and make more power . More duration should give more intake charge . But most likely you wont need to do that if your over 230 duration.

I think 5200 would be a good trap rpm for your car ... jmo...

[Curious George]

So all things being equal, if at 8 psi peak HP is at 5100 RPM, at say 15 psi peak HP would likely move up some to maybe 5300 RPM?

[charlie66]

That's up to the efficiency of your motor. At 30 psi mine peaked at 6250. At 38 psi it only peaked at 6100. So like Bruce said , you need to try some more things on the dyno to see what it likes and set it there.. ..

[v869tr6]

Originally Posted by Curious George

So all things being equal, if at 8 psi peak HP is at 5100 RPM, at say 15 psi peak HP would likely move up some to maybe 5300 RPM?

Your cam is a lot bigger then mine, and your numbers don't fall off as fast as mine do.
Without digging my dyno sheets out I think my engine made peak power at about 4900rpm with 13 psi, and about 5250 at 20 psi

[v869tr6]

Looking at my old cast rod and crank 462 with a ultra dyne nitrous cam I found some old wheel hp sheets

Max. power Max torque
8psi 389 467 @ 74mph don't have the rpm
15.6 psi 622 654 @ 4900rpm was 95mph
19.1psi 701 713 @ 5200rpm

[Curious George]

Great info, thanks guys.