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High Revving V8s
irvined - 21/6/10 at 08:52 AM

Hello,

I'm gathering ideas for my next project, (mid engined, rear wheel drive, full aero.) I had originally intended fitting a 4pot, possibly a boxer, I'm going for reasonable power output, in the region of 400-500hp.

The other day, there was a
post on here about an Audio RS V8, which revs to 8k, are there any other nice v8's that rev this high?

Options I've considered:

BMW M3 Engine: Redline 8400
RS4: Redline 8,250
LS Series: ~6000 (Too low)

Any others?

jossey - 21/6/10 at 08:53 AM

bmw m3 or m5 all the way.

:O)

get the LSD on the back and make very long 11's down the road :O)

tomgregory2000 - 21/6/10 at 09:21 AM

You want that lexus v8, the old one from the 400's i think, good engine

Its model number is 1uzfe

Have a look on lextreme

[Edited on 21/6/10 by tomgregory2000]

iank - 21/6/10 at 09:36 AM

Just out of interest why would you care what they rev to?

Surely the peak bhp and how it's delivered (wide or narrow band) is more interesting. Or is it purely a sound thing?

greggors84 - 21/6/10 at 09:53 AM

Ferrari 355?

Fatgadget - 21/6/10 at 10:09 AM

quote:
Originally posted by iank
Just out of interest why would you care what they rev to?

Surely the peak bhp and how it's delivered (wide or narrow band) is more interesting. Or is it purely a sound thing?


I too always liked V8s for their low end grunt.My old man used to have a side valve V8 Ford Pilot which he traded in for a Morris Minor traveler I think if you want high revs get a 4 pot.

nick205 - 21/6/10 at 10:10 AM

What sort of rev limit is there on boxer motors - Porsche, Subaru..?

Are they significantly different in that respect to in-line or V engines?

irvined - 21/6/10 at 10:30 AM

quote:
Originally posted by Fatgadget
quote:
Originally posted by iank
Just out of interest why would you care what they rev to?

Surely the peak bhp and how it's delivered (wide or narrow band) is more interesting. Or is it purely a sound thing?


I too always liked V8s for their low end grunt.My old man used to have a side valve V8 Ford Pilot which he traded in for a Morris Minor traveler I think if you want high revs get a 4 pot.


Its just personal preference, whilst HP/Torque is also important, I like engines that scream rather than burble...

I am considering scooby boxer as it revs high, seems pretty strong, and is nice and short, but recently have been thinking a V8 might be quite nice too

fha772 - 21/6/10 at 11:38 AM

Audi A8 4.2 V8, cheap(whole car for a grand or less) quite revvy, and non-Quattros are fitted with a trans axle(ideal for mid engined).

mgmiller - 21/6/10 at 11:45 AM

scooby engines only rev to 6500 or 7000 if you have the jap version

bimbleuk - 21/6/10 at 11:55 AM

Don't write the LS engines off quite so easily the LS7 engine for example has a rev limit of 7100RPM.

The lesser engies can be upgraded quite easily with valves, springs, lifters, rods, cams etc. to go higher. I believe the limit is more to do with the piston speeds as they are such large capacity. So stick to the 5.7 LS1 and upgrade the valve gear and rev higher. You should be making around the mid 400s to 500s by then so plenty of power.

[Edited on 21-6-10 by bimbleuk]

irvined - 21/6/10 at 01:25 PM

7000 is my minimum, so maybe the ls7, since they come with a dry sump as standard and seem to be bulletproof.

Does anybody have any cad drawings for either the scooby or the ls engine?

beagley - 21/6/10 at 02:38 PM

quote:
Originally posted by bimbleuk
I believe the limit is more to do with the piston speeds as they are such large capacity. So stick to the 5.7 LS1 and upgrade the valve gear and rev higher. Edited on 21-6-10 by bimbleuk]


Quite right about piston speed. You can also shorten the stroke, but then you lose some of that great v8 torque at low rpm. If you've got the spare change (quite a lot of it) you can get those ultra light pistons, conn rods, and crank to squeeze out every bit of engine speed/horsepower out of your v8. I've got a book at home that has the formula to estimate piston speed and horsepower and if someone hasn't posted it by tonight I'll throw it up here for everyone, although I'm quite sure somebody on here will have it memorized.

P.S. I LOVE the sound of V8s at 8-9k+ rpm

bj928 - 21/6/10 at 03:42 PM

depends on you budget, the 32v v8 ford engine out of the 96> mustang has a rev limit of 7000, with 305hp or 320hp, or supercharged from factory in the cobra in 2003/4 with 400+hp, i have a contact for the GT40 gearbox that is 6 speed and bolts straight to the 32v engine giving it a mid engine setup.

also the supercharged or N/A Jaguar v8 revs to 7k

fha772 - 22/6/10 at 09:08 AM

I would still go for the Audi 4.2.

The standard engine revs to 7000rpm.
(with some tweaks it hits 8000rpm, in the RS4)
It already has the trans axle fitted, for mid engine use.
(you can even fit a 6-speed out of an A4 2.0, for under £500, it will take 500+bhp)

It's 340ish BHP, as standard and can be taken to about 450-500 BHP, for the money you can get back from selling the parts off of the donor A8.

So basicly, you can buy an A8 for around £1000, you can sell the parts you don't need for around £1000-£1800.
Then spend about £800-£1000 on the engine.
HEY PRESTO!! A 400-500 BHP alloy V8 and transaxle for free!!!

Where's the downside?

beagley - 22/6/10 at 12:35 PM

Sorry guys, I completely forgot to get out my auto math handbook when I got home yesterday. On a side note, for any of you that are REALLY into math I found this forum for engineers that is discussing how to figure out the maximum piston speeds for various engines.

Click Here

My head started to spin towards the bottom of the thread, but I found it to be quite interesting (and yes, I am a math nerd).

Beags