LS Tuning

[GarethGTR]

Hi All

I have read with interest another post where 700HP is claimed from an NA engine.
Now, I am yet to buy the engine but have my heart set on an LS7. So I am wondering what the route is to upping the power at what cost / reliability.

The stock LS7 is 505HP and apparently just a GM cam take this to about 600HP.

I have designed the rest of the cars systems (transmission, fuel system etc etc) to handle well over 1000HP even with slicks, although I most certainly would not want this much power, but 700 to 800 would be very nice :-) - Like the other OP I would like to get in the ball park of the record breaking car.

Any thoughts? Or should I consider an LSx with ally block?

Oh, and if it males any difference, I can seriously and safely up the fuel pressure if required.
I have a close friend that tunes bike engines for a living (at world champ level) and wonder if it worth the hassle of taking the LS7 heads off and gas flowing them?

BTW, has anybody got a workshop manual for the LS7?

Gareth

[738 driver]

Out of the crate a 7 gives great results and with a cam swap (although a GM stick would not be my choice) would be even better. However if you have intentions on getting into the true 700+ NA bracket then many of the crate internals would be best upgraded. So it might be worthwhile to look at a stronger base unit as your starting point with the knowledge it will handle future development.
LS and race bike head work do differ considerably though, two big valves over four or more small ones combined with strange shaped bores/pistons/heads need a completely different approach.
For N/A power you cannot beat cubic inches, just keep a couple of bore sizes in your back pocket initially.

good luck.

[02PRUV]

I have a mate with a Vette that recently did full exhaust, cam, FAST intake, ported TB, full CNCed LS7 heads and they ended up getting 485whp strapped down real hard on the dyno. They let the straps off a bit and and made 500rwhp. Going by that it would be making around the 620bhp mark and the tuner thinks that the aftermarket exhaust on it would still be too restrictive. So you might find with a better exhaust 640bhp would be achievable. Wanting more than that the easy way to do it is remember the good old saying "you can't beat cubic inches". A LS7 is 427ci the engine I'm getting built is 454ci.

[Swiss_Toni]

Have a chat with Pete Knight at Knight Racing Services as he builds and dyno's his own engines. On top of this you can't bet his customer service.

He built Stuart's and my LS7 (NA 705 bhp+), if Stuart is around I'm sure he will also back me up on this.

([phone]

http://www.knightracingservices.co.uk/

For mapping, especially MOTEC, get in touch with Lee Penn. He works with Pete and does some magical things and to top it all off steller customer service.

http://www.lapengineering.com/

Greg

[Gulf LS3]

No do it yourself Gareth, you seem a very capable guy.... buy a crate LS7 and start from there ie a nice custom cam and flow and port the heads etc. Motec is massively over priced imo, if you run fairly standard(cam specs so important) ie upto 700bhp the GM ecu, loom are all useable with great road manners unlike some engines we could mention.

Like Dom has said before there is nothing like building your own engine and hearing it fire up, its a bit trying sometimes but ultimately worth it!!

[Boosted LS1]

Ls7 heads are wonderful things in their own right and fully cnc'd by GM. I wouldn't interfere with them. If I was building a modded ls7 I'd cam it (maybe change valve springs to suit) and probably fit some forged pistons with some Total Seal gapless rings. I'd rebalance the crank and probably leave it at that.

[V8 Vum]

Exactly as I had done....638bhp dyno!

[LMRACER]

I have alsoheard that changing the crankshaft( to a Callies or Bryant) and the valves (heads fall off)both are well known issues with built LS7's

Edited by LMRACER on Thursday 2nd December 14:10

[Boosted LS1]

^ Can't see it myself. The stock crank is a lovely piece of kit. The callies is a little bit lighter but you can see how they've changed the counterweight design and made them smaller. I'd prefer to stick with the Gm design as they'll have put a lot of development into it, the engine package as a whole. As for the Ti valves, I've heard a rumour but would imagine tht if the rpm envelope stays the same the valves should be fine. You could always fit heavier ones if you wanted to but I'm sticking with all the GM parts for now.

[LMRACER]

Stock cranks crack on the fillet ,they dont break but they do crack..(I have three of them) , the exhaust valves fail regularly ,call Ferrea and ask about stock ls7/ls9 exhaust valve failures.

Edited by LMRACER on Thursday 2nd December 16:48

[GarethGTR]

Hi All

Port / dont port, flow / dont flow, replace valves / dont replace valves, replace crank / dont replace crank

Aaaaaaggggghhhh! where is that bottle of JD? this is too much - thanx for the advice guys :-)


I am happy doing the work myself, and feel okay with flowing, porting etc. I dont really want take down the bottom end and so want to keep it to head work. Why? well realising more more power from more efficiency is a great way to do it.

But what to do? there are so many conflicting ideas...

Gareth

[Boosted LS1]

LMRACER said:

Stock cranks crack on the fillet ,they dont break but they do crack..(I have three of them) , the exhaust valves fail regularly ,call Ferrea and ask about stock ls7/ls9 exhaust valve failures.

Edited by LMRACER on Thursday 2nd December 16:48

What sort of use were the engines subjected to?

As for valves I'd expect a valve supplier to make the most of a marketing opportunity. If it was so bad wouldn't you expect GM to use Ferrea valves instead of the Ti ones they use at the moment? I've heard rumours but not really seen any facts or engine recalls so can't say how much of a problem these things are. I'd like to know though.

[Swiss_Toni]

Wasn't the valve dropping issue down to a dodgy batch of stock vales a while back?

[Boosted LS1]

Swiss_Toni said:

Wasn't the valve dropping issue down to a dodgy batch of stock vales a while back?

I don't know but hopefully somebody will be able to shed some light on it if this is a serious issue. I've a pair of ls7 heads, built up with stock valves waiting to be used on my 427 Darton TT. If the valves are suspect I'll change them but as far as I know GM are still producing them.

[738 driver]

If the plan is to blow the motor GM have recently released their lower compression LSX 376 purpose built ready with forged pistons great heads etc etc.....for very reasonable money. The LSX block might be iron but would stand as much as we are likely to ever demand... has lots of rebores/ capacity potential and wont be too far off what the original car was designed around weight wise. Not sure Id spend $12000 on a limited 7 when $5500 will get you very similar performance and lots of options in your back pocket..
Plenty of ways to skin a cat...!

[V8Dom]

Gulf LS3 said:

Like Dom has said before there is nothing like building your own engine and hearing it fire up, its a bit trying sometimes but ultimately worth it!!

Its certainly is worth it, especially when there are gains to be made and youve made them. The sound of a race engine when youve just built it is fantastic....


And as said a bike engine is so so different....been there,seen it,done it 2 British Dragbike championships... this is far far more technical and proper old school,


Mines all in bits now, neatly labels and many options are being looked at. Id love to TT my engine or even fitted the dreaded TT diesel I always jest about( but there is no gearbox for that due to the torque otherwise other teams would build diesel LeMans cars)) So this year Ive decide to strip the car but Im on a careful budget. Im also looking at building a Cross over exhaust and doing some interior mods if I get the time. If you get stuck , just give one of the guys here a shout and the can always finish the build for you , but at least you can say you had a go..

Dom

Edited by V8Dom on Friday 3rd December 20:04

[Brummmie]

Heres my LS3 416CI effort..

http://www.youtube.com/watch?v=DMjCFiqMGUY

[GTRene]

wow, must be a fast Cerbera.

[GarethGTR]

Hi All

After considering all of your replies, I am left wondering is the significant extra that the LS7 costs over the LS3, is it really worth buying an LS7?

You experiences and opinions would be appreciated.

Gareth

[XTR2Turbo]

Another vote for Peter. Mine was the first 700 NA Kinsler LS7 he built for my Ultima.

I understand he can now get closer to 800 bhp