7446 rpm redline recipe?

**MotoTuner** · 11-22-2016 09:20 AM

Hi Audi Community,

I want to prep an old Audi 2.7t engine (from s4) to safely rev to 7446 rpm in a 2WD kit car project. Power goal is 400whp on 93 octane fuel and 440whp on ethanol. My question is, what do you folks recommend as the minimal requirements to rev this motor to 7446 rpm safely? Is there a specific valve+spring package you'd recommend that is proven to last at this 7446 max rpm without being overkill?

As far as bottom end, my plan is the following:
1. IE connecting rods (w/ arp bolts & new bearings)
2. RS4 Main Crankshaft Bearing Caps (w/ arp bolts & new bearings)
3. New oem piston rings
4. New oem head gaskets (w/ arp head studs)
5. Fluidampr Crankshaft Pulley
6. New oil pump + water pump
7. Gt2554r turbos (w/ custom tubular manifolds built by me 😀 )

**Monty23** · 11-22-2016 09:48 AM

I run supertech valve train in my heads up to 8500 rpm. The spring/retainer kit should be all you need for 7500rpm. I used to rev my completely stock heads to 7500 rpm during spirited driving and had no issues.
I would run a set of 2.8 30V v6 intake cams in your heads as well.

**julex** · 11-22-2016 11:45 AM

The only part of 4 cycle that is commonly affected by valve float is the transition between exhaust and intake stroke where exhaust valves float could result in valve to piston collision if exhaust valve doesn't close on time.

A set of uprated exhaust springs with titanium hardware is all you need to be able to rev high without any problems. If you can afford doing intake springs and perhaps going with complete replacement of valves to something "Better", do it as well.

**S4James** · 11-22-2016 12:25 PM

I dont often see a set of exhaust side only valves and retainers.. In fact im not sure ive ever seen it.. Is this something someone like supertech is typically willing to supply?

**MacDaddy** · 11-22-2016 04:02 PM

Im not sure what the concern with the redline is, but if all you want is 400hp a stock block with k04's will get you there

**01audia4** · 11-22-2016 05:10 PM

Originally Posted by MacDaddy

Im not sure what the concern with the redline is, but if all you want is 400hp a stock block with k04's will get you there

Was thinking the same thing. Even then k04 / F21 will fall off before redline. You can easily obtain your power goal without doing heads e85 F21 built block or not.

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**MikeyB3** · 11-22-2016 05:24 PM

If you build it, it will rev...

**01audia4** · 11-23-2016 07:03 AM

Originally Posted by MikeyB3

If you build it, it will rev...

It will. Unless you have a turbo that would be blowing hot air at that range.

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**Lanorg** · 11-23-2016 05:34 PM

Guys, I think since he was more specific with his rpm range, he is trying to hit specific gearing to achieve specific speeds in a particular gear. The horsepower is the ballpark figure but rpm 7446. That's damn specific, so considering the kit application there may be other goals than just, "how much powaa?"

**MacDaddy** · 11-23-2016 08:14 PM

Theres more to gearing than what an engine revs at, if hes going to look at one aspect and ignore everything else its not going to work out.

**MotoTuner** · 11-24-2016 01:17 PM

Thank you ALL for your specific technical recommendations.

Originally Posted by Lanorg

Guys, I think since he was more specific with his rpm range, he is trying to hit specific gearing to achieve specific speeds in a particular gear..

This is exactly the reason for the 7446rpm limit. (gives Lanorg bonus points

)

Regarding the proven K04 turbos upgrade, I would need an Electronic Wastegate Actuator (of some kind) to open the wastegates after ~7,000 rpm so I don't overspin the turbo and run with intense back pressure. This seems like it would be perfect for an "uber" responsive street friendly setup.

Regarding valve spring retainers, is there a better material than titanium that will last more mileage? I ask because I'm staying under 7500rpm and would prefer maximum longevity if possible.

**DieselElectric** · 11-24-2016 01:45 PM

I'd just run a stock engine, take the money you save and have a spare engine.

I've run my f21 car to 7500 more times than I can count. 175,000 miles and the rings on cylinder 5 took a shit before the topend. (In the midst of a rebuild but, reusing old heads and valvetrain with a lap and new valve seals.

**Blake2423** · 11-24-2016 09:40 PM

I would say your stock heads will do fine. My k24 build was running to a 7500rpm redline and power wasn't falling off up there. I would say if your goal is that rpm then your money would be best spent elsewhere.

**rguil** · 12-02-2016 05:45 PM

Are the Supertech springs good to rev to 8 constantly? Anyone have experience in this? I have Inconel single keeper exhaust valves but I've been thinking about pulling off the heads and putting new springs and intake valves in.