Too much power ????

[ZHeadV8]

Hi guys,

 

have done due dilligence and searched but not come up with any answers.

 

My car is in build and will have an LS6 / T56 combo so should be pretty rapid. I have drooled over Haans' twin turbo, read about superchargers, looked at Darius' car etc etc BUT ..............

 

The guys in the UK who I have to say I respect and trust because they really do know their stuff tell me that anything more than 400BHP in a 240Z, even a seriously well strengthened one, will become almost undriveable, particularly when driven hard round twisty tracks or launching for a quarter mile.

 

They have advised I go for a standard 405BHP LS6 with a Cold Air Intake and that this will be more than adequate power.

 

What difference can I expect from a CAI ? Will it get back some of the induction noise I loved with triple Webers ? Will it increase power or throttle response ?

 

I have read differing views on the benefit of individual throttle bodies (have to say I quite like the idea if it is available for an LS6) but no real definites on CAI's.

 

Can anyone shed any light for me please ?

 

Cheers

 

Andy F

[Phantom]

Cold air intake will help on those hot days if you're going for all the gusto the engine can deliver. Trust me - you'll definitely get all the engine sounds you'll want. These cars aren't aht well insulated. You won't hear the suck of the intake, though, if it's in front of the radiator.

The LS6 is an excellent choice for combination of power, reliability, and balance. I would suggest getting the 3.70:1 R200 LSD out of an 87-89 Z31 turbo car. It will definitely improve power transfer. My 365 HP LS1 pretty well overwhelms my 215/55-16 Kumho Supra 712 street tires in first gear but they stay pretty stuck from then on. Get some sticky tires and you should be fine with the LS6. The biggest problem you'll have is rear wheel hop and keeping the half-shaft universals from detonating if you drag race a high torque / high hp car a lot. It'll do fine for autoX or road courses.

You definitely will want frame rail reinforcement on a 240Z along with front and rear strut tower braces and, at a minimum, a four point roll bar.

[ZHeadV8]

Thanks,

 

I only wish we had really hot days in England

 

I have a NISMO 3.9LSD in an R200 already and am having custom driveshafts because I am convinced modded 280 ones will shatter - I know everyone uses them but I just have it as a bee in my bonnet.

 

Tryes will be 265 / 40 / 17s on the back which are all negative offset so sit under big arches.

 

The chassis is being seriously strengthened, full cage, longer and thicker rails, thicker floor, seam welded panels and apertures eveywhere.

 

Basically the build spec was put together to cope with 700RWBHP but I am being advised against it left right and centre, just wondered what the concensus was ?

 

How much power is just right to give brutal acceleration but not be so far out there that the car shakes it's booty at the slightest hint of too much throttle ? I have nothing to go on because Hybridz are simply not cricket over here !!!

 

I would like lots of grunt but useable grunt and not just to have a donut machine.

[cyrus]

I have had a 330 rwhp ls1 z and a 406 rwhp twin turbo z and can say that undrivable is completely wrong. You must have the car set up right and use more and more disernment as the hp rises. Both cars I have had are pussycats. Even my wife has driven.

[Phantom]

With a T56 you will find first gear almost unuseable with 3.90:1 gearing. I'm marginal with 3.70:1. If you're planning to end up north of 450rwhp I would strongly recommend looking for some 3.36:1 gears. They are available. While we're on that, though, you may be reaching the limit of the R200. You might want to get a rating off Nismo. You may also want to consider a 5-spd rather than the T56. It will be lighter and you can get them stronger. You probably wont need the 6th gear unless you're planning on speeds in excess of 250 kph. which is pretty close to the aerodynamic limit of an S30.

[Guest zfan]

I must agree with Cyrus as my wife has driven my low 11 second 1/4 mile 240Z and was suprised to find it was so docile until you mashed the gas peddle. I am approx. at 400 rwhp.

 

Mike

[grumpyvette]

that longer pedal (accellerator) can be depressed to a lesser extent to lower the engines output significantly.......I had a corvette a few years back with a full roller 13.7:1 compression 496 injected big block chevy with direct port nitrous injection that put out ( Ill say ,well in excess of 600 rear wheel hp (you would not beleive the real numbers)

I drove that on the street occasionally with no problems

not getting the rpms above about 3500rpm and not hitting the nitrious or the secondary fuel pump and useing your skills as a driver made the differance between laying twin 14" wide black rubber tracks for hundreds of feet or just rumbling along with the engine between 1200rpm idle and short shifting at 3500 rpm with the pedal barely depressed

[patzky1]

It sounds like your friends are afraid of their cars being bested by your lil' Z with the n/a 400 hp LS6 and are discouraging you because anything over that will be even more embarrasing. Am I right? The hot Ferarris and McLarens, etc. are over 500 hp and are driveable. It all depends on the car's setup and driver's skill level (and maturity) :>

 

Keep in mind that you have a standard transmission (no crazy high stall torque converter) and a modern fuel injected engine. These both will make your job of driving like a pussycat easier if you want to IMHO. As stated before, you'll probably be doing a lot of second gear starts with a T56 and 3.90's without DRs or slicks.

 

Of course, you can always start with a stock engine, get used to the car, and then go wild with it. It's easy enough to go back to mild from wild if need be.

 

My 2 cents,

 

Pat

[pparaska]

I believe one key to a drivable high horsepower car is the throttle linkage geometry. I have a 375 crank hp 327 in my 240Z and the part that makes it a bit touchy to drive is the 4 barrel 700cfm non-progressive Throttle Body Injector (Holley Pro-Jection). All 4 barrels crack open at once. After lifting your foot off the pedal to decelerate, then at a low speed in 2nd gear (1.98:1 with 3.7:1 rear and 25" tire) if you tocuh the pedal anything like you would in another car, the engine comes on hard and jerks you around. I plan on making a cam/cable linkage on the TBI to slow it down initially.

 

That said, start with the LS6 and when you're ready for it (you WILL get used to it) throw in the cam/headers/heads/etc. to go to 500 crank hp.

[ZHeadV8]

Good advice thanks Guys,

 

I do not think that these guys over here are worried about getting smoked at all, the concerns are how hard it would be to feather the throttle around a race track for example - one lapse in concentration, one blip too hard and I could be off the track.

 

On a drag strip the software computations have shown a faster run at 450BHP than 500 because of potential traction issues - as I say, I have nothing to go on, nor have a lot of the people helping me other than software computations and gut feel (Hey, I can justifiably be in two minds because I have two sets of guts)

 

The question is really more about traction I suppose than power.

 

The five speed is an interesting idea - Mike Kelly advised me on a 5 speed way back but I had six speed stuck in my head. Could I get a five speed with first gear the same ratio as second in the T56 ? WHich one would be best ?

[ZHeadV8]

I believe one key to a drivable high horsepower car is the throttle linkage geometry.

 

VERY good point pete, do not want it "on or off". I am having discussions at the moment whether it will be better to install a cable linkage or keep the throttle by wire system and map the way the juice comes in.

 

I could run a normal street map with a softer throttle attack and a competition one with a bit more grunt early on.

 

ANy views ??

[deMideon]

I have a 280Z with 410hp at the wheels, a T-56, 3.54 gears, and an aluminum flywheel. I find it to be relatively easy to drive. Not too much power for me, very easy to control. A very well balanced car.

[ZHeadV8]

SO the consensus is obviously that 400BHP is good and controllable....... what about 500......600 .............700 ?

[Pop N Wood]

You might want to read some of JohnC's posts about the road manners of a Z with such low profile tires. He definitely knows more about making a Z handle than I ever will.

 

Also, if you bought a crate LS6, if they are anything like the crate LS1's you might be pleasantly suprised. Every car magazine I have read that used a crate LS1 for a project measured an out of the box HP of over 400 HP. Here is one example

 

http://www.popularhotrodding.com/enginemasters/articles/hardcore/0409em_gmpp/

 

The article is about carbing an LS1, but note that the stock engine rang up 429 HP. With a cam and new valve springs they measured over 500 HP.

 

Hope you get a chance to dyno your LS6 before it goes in.

[Scottie-GNZ]

The main problem with 500, 600hp is in your right foot and the grey matter between your ears. Understand what you have under the hood, RESPECT it and resist the urge to "showoff". Oh yeah, a pair of really sticky rear tires also helps Somewhere around 520rwhp and I use fat drag radials as my everyday rear tire. Anything else is instant wheelspin or worse, a spinout. With such power at your command, the appropriate chassis, suspension and brake upgrades are a must.

 

With those and your discretion you have a really fun and suprisingly streetable car. BTW, my car is turbo and if the 500-600rwhp requires big valve heads and a rumpity-rumpity cam, then in-town driveability will not be so enjoyable.

[EvilC]

The urge to "showoff", good luck.

[Turbo Meister]

According to my Dyno-Sim computer program, my TT383Z is developing a maximum of 750 hp and 822 ftlbs of torque at 17 psi at the flywheel. I'm finally at the point where the carb, fuel pump, and ignition timing have reached a happy compromise to allow smooth low speed cruising and WOT blasts (knock on wood).

The good part is that I never have a problem with insufficient power to blend into the freeway traffic from the on-ramp.

My 383 engine only has 8:1 compression ratio and is not very radical. It's the turbos that generate the power but only when I want them to. But power is not enough. The chassis, transmission and rear end need to be able to handle it. And 12" wide sticky tires are handy for getting it to the ground.

At MSA, last Sunday, the Z idled like a stocker for at least 30 minutes while inching forward to get lined up. Then, while jockeying for position, I accidentally turned on my fuel pump booster and turned off my fan. Took me a while to figure out why the Z wanted to stall and get hot.

...now if we could just eliminate the human factor....

Hanns

[Guest FasterbyFosta]

According to my Dyno-Sim computer program' date=' my TT383Z is developing a maximum of 750 hp and 822 ftlbs of torque at 17 psi at the flywheel. I'm finally at the point where the carb, fuel pump, and ignition timing have reached a happy compromise to allow smooth low speed cruising and WOT blasts (knock on wood).

The good part is that I never have a problem with insufficient power to blend into the freeway traffic from the on-ramp.

My 383 engine only has 8:1 compression ratio and is not very radical. It's the turbos that generate the power but only when I want them to. But power is not enough. The chassis, transmission and rear end need to be able to handle it. And 12" wide sticky tires are handy for getting it to the ground.

At MSA, last Sunday, the Z idled like a stocker for at least 30 minutes while inching forward to get lined up. Then, while jockeying for position, I accidentally turned on my fuel pump booster and turned off my fan. Took me a while to figure out why the Z wanted to stall and get hot.

...now if we could just eliminate the human factor....

Hanns[/quote']

'

Are you widebodied? 12 inch tires would be awesome. Im building my 396 lt1 with a GT4276 right now, and the N/A 396 had traction issues, so Im hoping to fit a bigger tire...

[Turbo Meister]

'

Are you widebodied? 12 inch tires would be awesome. Im building my 396 lt1 with a GT4276 right now' date=' and the N/A 396 had traction issues, so Im hoping to fit a bigger tire...[/quote']

 

Yes, I'm widebodied:) but my Z is not. The Z is back-halfed with tubs and a narrowed Ford 9" differential. With the power of your engine combination you will absolutely need wider and stickier rear tires.

Hanns

[Guest FasterbyFosta]

Yes' date=' I'm widebodied:) but my Z is not. The Z is back-halfed with tubs and a narrowed Ford 9" differential. With the power of your engine combination you will absolutely need wider and stickier rear tires.

Hanns[/quote']

 

Yah, im looking into a better tire setup. I have a R230 diff, and 24.5/8 slicks on the car, but they probably wont hold up to the 800+ hp I should be capable of...

 

I really want to keep the R230 setup, but I havent found a reasonable looking and priced widebody setup....

 

The search continues....