Gen III Power Options

[13COBRA]

Looking for some advice.

I have a heads/cam package, throttle body and tune now. It puts down 630/617.

What are my options for more power? Say in the 700-750 range?

[J TNT]

Call Scot at Prefix. 9 litre option. Over 750 hp and a Great Torque curve.

[13COBRA]

Call Scot at Prefix. 9 litre option. Over 750 hp and a Great Torque curve.

I think if I were going to spend that much I would go with a built destroked engine from Kevin.

[J TNT]

Also a good option depending what your parameters are and how you use your car…..

I think if I were going to spend that much I would go with a built destroked engine from Kevin.

[13COBRA]

Also a good option depending what your parameters are and how you use your car…..

It's a Comp Coupe.

[Aevus]

Other than turbos and SC, the only two options are 9L or destroked (7.6L ish) 7,500rpm+

I pushed my gen3's 8.3L to peak HP @ 6,700-6,900rpm but I wouldnt dare to track it and I'll be lucky if I get 670-680whp when I'll dyno it..

[13COBRA]

Other than turbos and SC, the only two options are 9L or destroked (7.6L ish) 7,500rpm+

I pushed my gen3's 8.3L to peak HP @ 6,700-6,900rpm but I wouldnt dare to track it and I'll be lucky if I get 670-680whp when I'll dyno it..


That's what I was thinking as well.

[Aevus]

Looking for some advice.

I have a heads/cam package, throttle body and tune now. It puts down 630/617.

What are my options for more power? Say in the 700-750 range?


If you can live with 680-700whp, then upgrade your valvetrain as much as possible which implies Ti or hollow valves + shaft mount rockers + conical springs w/Ti retainers and all the lightweight goodies to spin the motor 7-7,2k rpm (along with a new cam obviously and 3.73+ gears)

That was my original plan but couldnt get hollow valves from Ferrea in time nor shaft mount rockers from T&D (2022 was a nightmare for parts supply)

Next bottleneck(s) will be the crankshaft and the oil system. Other than the swing arm oil pan, I'm not sure about the differences on the Compe Coupe vs gen3

[Aevus]

damn I'm getting old, I'm forgetting about my own project...

So, yeah, you have to get a higher CR if you want to play with a much bigger cam otherwise it's not gonna be tunable and you'll leave power potential on the table

To give you an idea here is the list for my project:


A little update on my ''high-rpm'' project:

as mentionned above I went with a cam that is about the maximum possible -just before it makes no sense- and it's a very tight fit:

10.9:1 compression was the max possible with valve clearance.
256 @ 0.050'' exhaust duration is also a challenge for valve clearance.

The somewhat limited exhaust lift (0.554'') for such an agressive cam is actually a bet we did: Less strain on the valvetrain, better clearance for higher compression, lots of duration, all for peak power target between 6,700 and 6,900 rpm.

Luckily, my ported Gen 3 heads flows extremely good on the exhaust side: 241 CFM @ max lift but more importantly, it flows better than a stock Gen 4 heads all across the board. Heat-wrapped headers will probably help the scavenging as well.

On the intake side, they deliver 315 CFM @ max lift (0.596'') which is short of about 10 CFM from stock Gen 4 heads and short of about 15-20CFM from 0.400-0.500'' lift. Not yet sure if the cam will max out the intake flow yet... If so, I always have the possibility to put shaft mount rocker with higher ratio and get 325 CFM with higher lift.

Unsure which bottleneck gonna hit first at high RPM: hyd lifters ? Camshaft ? Intake side flow ? Valvetrain ? Oil system ? (hope not lol) or even gas pump ?

My bet would be the valvetrain (valve float) and not the heads, even less the cam. But I may be wrong, we'll see...


Basically the whole engine is new, with only the stock crank (machined + balanced of course):

- Forged Mahle/Callies pistons and rods (lighter 4032 alloy)
- 69# injectors
- Ferrea valves competition plus
- Conical springs
- Titanium retainers
- 3/8 0.080'' pushrods
- Prefix ceramic hyd lifters w/ tru-arc
- Prefix high-volume oil rotor
- Fidenza aluminum flywheel
- M&M heat wrapped headers
- 3.5'' exhaust
- Hiflow cats

Pretty much the max I could do for a high-rpm non-destroked NA project, besides titanium valves and shaft mount rocker with even bigger pushrods. At some point, you really have to worry about the stock crank, oil system, fueling system, cooling system, transmission, etc.. it never ends and the law of diminishing returns kicks hard. Lots of risks, time and money for few extra HP... Not worth it I think.


https://driveviper.com/forums/threads/28790-What-really-limits-our-engines-to-rev-higher?p=463669&viewfull=1#post463669

[Fatman2006]

Why did everyone skip over NO2, with supporting mods?

[GTS Dean]

Because Nick has a Competition Coupe - a track only car.

[efnfast]

Why did everyone skip over NO2, with supporting mods?

It's 2022 not 2002 ... does anybody even use NO2 anymore?

[Ramtuff]

It's 2022 not 2002 ... does anybody even use NO2 anymore?

It still works the same in 2022 as it did in 2002.
52729