v8robert

Have just joined the site and totally confused and bemused by all the tech speak . I have a gd cobra 427 replica with the LS6 engine on board. I'm lookng for about 500 bhp. I do drive the car on a daily basis however track it as much as possible - Spa and the Ring to name a few, so not too concerned over a slightly choppy idle if it means more grunt.

There isn't much knowledge re the LS6 in England and so I need your help I have sourced a guy who can port my heads however need advice re cam +- rocker set.

Any opinions on the pro magnum 1.85 rockers and comp camshafts ? Keep it simple My expertise lies in the human body, not the makings of an engine

Apologies for covering old ground !
Cheers
Dr Rob

CaptUSA

iTrader: (5)

Greetings from the U.S.

500HP is a lot of guts, how tame do you want it to drive, and how many pounds are you looking to spend?

MTI (A sponsor on site) has a 450hp heads / cam package they sell for around $6K USD. That price was installed I believe, so check them out for straight sale price. You can also look into a supercharger setup for really tame power.

As with all things though, it's give and take. How nice do you want her to be when you're stuck in traffic, how much money do you want to spend, are you willing to use NOS, will you drive train handle the power you're looking at pushing on her?

I obviously have no idea how serious you are about cars, but 500 hp in a car the size of a Cobra may be difficult to handle for an amature (myself totally included) 350 -400 hp seems like it would be perfect. Put you in the mid 12's on a quarter mile sprint. (I don't know how far you guys race in kilometers, but mid 12's in a quarter mile are very nice)

Good luck in you quest. As you come up with specific questions, take a second to post them up here onsite. There is a LOT of knowledge here for this particular engine.

Cheers.

calongo_SS

iTrader: (7)

Assuming you have stock 346 cu. in. 500 rwhp is going to be pretty difficult & very expensive NA. However 450-470 shouldn't be too hard if you've got some money. Not sure on the specifics of your conversion, but I'm assuming it is fuel injected, and you already have headers and other bolt ons. I'd go with a FAST 90/90 intake, hand ported AFR 205's (or 225's for that matter) and a mid to low 230's duration cam with stock rockers. This will probably run you about 4 to 5 grand (2000 pounds ???) in parts.
Or you could slap a blower on it and be about the same place power wise & cost wise.

blkZ28spt

500 horsepower, or 500 wheel horsepower? 500 horses is much easier to obtain, obviously.

jub jub

If you have an LS6 you can easily make 500 HP with the addition of AFR 205 heads and a nice Comp cam such as the one in my sig. Of course that's figuring you already have headers and some kind of low restiction air filter. Add an underdrive pulley and your good to go! The cam in my sig has a nice chop at idle and behaves well on the street. In fact it's hard to tell it from stock after 2000 rpm, that is of course, until you put your foot down.

SPG

iTrader: (3)

Hello Rob - glad to see you survived le mans!

This breaks down into a couple areas for consideration.

Emmissions - I cant remember if you have any emmissions issues, but your cam choice will deopend on wether or not you have to comply. for example it is usually accepted that a 224/224/114 cam is about as large as you can go and comfortably pass emmissions, depending on the emission levels required.

Next is drivability. Ive had cammy engines before in daily drivers (albeit carbs) and they are a pain to use on a regular basis. Tuning can make all the difference with the LS ECU, but If it really is a daily driver, then I'd accept 5% less performance, for 50% improvement in road manners any day.

Heads and cam will get you to where you want to be.....and if you are changing the cam, then you can spec the lift to wherever you want it and no need for the expense on rockers

XTrooper

Fellas, he states he's "lookng for about 500 bhp," that's brake horsepower aka "at the flywheel."

That, as we know, can be fairly easily managed with a good set of heads and a "not-to-big" cam.

v8robert

Cheers for the replies boys .
Just to clarify a few points. I am going to get my heads ported by a reputable guy in the UK, however can't come to a decision about the choice of cam +- rockers.
I do drive this car on a daily basis and so don't want a pig at low revs in traffic, yet at the same time want a significant improvement over the stock cam. I think anything over 500bhp at the fly wheel will break traction too easily in my cobra that weighs 950kg.
I have no issues over emissions as it is classified as a kit car and hence is exempt. I also have a manual TKO2 gearbox that should stand up to the job, as for my crank shaft we'll have to see .
Surely changing the rockers to a higher ratio is a good idea as well, however i beleive some aftermarket cams will need some extra mods for this to work. I don't want a lot of work just a good reliable exchange that will put the fear of god up me
Cheers
Rob

calongo_SS

iTrader: (7)

I'd go with a mid to low 230's cam w/ lifts in the .59x area as I stated earlier w/ a good dual valve spring, hardened push rods and stock rockers, or the crane/vinci acceralted lift stock ratio rockers. Check out the cams at FMS, you really can't go wrong with any of those (F11, 13, 14). It'll make good power, have a somewhat choppy idle and still be very driveable.

777

iTrader: (21)

I don't see the need for getting different rockers. The stock ones should be fine, unless you just have money to burn. Get an f-13 and get your heads ported and you should be fine considering you will have headers, intake, exhaust, etc...

marco427

Anyone who uses a Cobra replica as a daily driver in England's crappy climate is a real man. For what it's worth, take a look at this site for additional pseudo-Cobra info: http://www.clubcobra.com There are a bunch of Aussies running LS1/LS6 engines in their Cobras who post there, and they're a generally power-mad crew.

BrentB@TEA

We have had our stage 1.5 heads with a 228 cam make 54x HP on an engine dyno. 500 should not be a problem even with a significantly smaller camshaft. Our ported 5.3 1.5 heads and camshaft package is $1900.00 US plus shipping.

BUYAMERICAN

Actually it's new ground.

I writing an article for one the magazines at present for my 427 Z06 street/race car with very reasonable duration/lift cam with 1.85 Comp Pro Magnum Rockers. Should have preliminary dyno by next week. I guess close to 600 rwhp(with only a 10.7 compression(endurance/street motor), torque at over 500 at 3200 and over 500 at 6,000. My heads flow 347 cfm at .600 and 299 cfm at .450. Running a port-matched FAST 90.

Stay in touch.

v8robert

Thanks for all your replies. Will contact FMS for some more info / pricing.
As for being a real man driving a cobra on England's crappy roads, no, just have a screw loose. Keeps me insane in a sane world

Laters
Rob

BAN-LS1

iTrader: (16)

"No idea What You Are On About !" <-- I'm still trying to figure this out???

Happy Jim

You guys speak in a language we know nothing of last time I looked a Goat was called billy and ran up mountains apparantly it's a car over there

CaptUSA

iTrader: (5)

DONAIMIAN

iTrader: (18)

If my goal was 500bhp Id shoot for it cam only and not bother with pulling the heads.

v8robert

The guy I have sourced in the UK to port the heads obviously does not have the experience of some of the companies in the states. Is there any advice you guys could give to me on what to ask or specify to aid getting a good job done ??

Cheers
Rob

zamboxl

iTrader: (1)

do not put 1.8 rockers i repeat DO NOT PUT 1.8 ROCKERS on an lsx engine it will severely limit ur cam choise, and its a waist u will get better gains with a slitghtly bigger cam and 1.7 rockers, and drive better, than with a slightly smaller cam and 1.8 rockers, and did i already mentioned 1.8 will severely limit ur cam choise.