The V8 Owners Forum -

Hey Guys,

I currently have a 3.9 in my mgb and am planning swapping with a low mileage 4.6 I bought about a month ago. What's the maximum shot I can use with stock internals. Reliable and occasional use - need to swat those pesky mustang gt's and rice burners from time to time.

Regards Tony

p.s. Great site - reviewed every post from beginning!

The 4.6 will handle 100 shot all day long. Once you go over this you need to increase piston ring gaps. With bigger ring gaps the 4.6 will handle a 150-180 shot. But repeated use will see the pistons cracking eventually. I have fitted Omega forged pistons in my 4.6 now and its been running a 240 shot all last year. And next month I will be out running a 300 shot.

As long as the ignition timing is set accordingly, and you deliver the gas via a progressive controller, the stock 4.6 will take lots of abuse.

Thanks for the response Perry. I figured you'd be the one as you seem to be the resident go to nos guy.

I'm running an lt77 5-speed and 3.07 dana posi. Obviously, traction will always be a problem - especially with street tires. The stock cam appears to be fairly decent for this application - short exhaust duration/wide lca. With peak tq at approx. 3000 rpms, what are you're recommendations regarding progressions - 50@1st/1500, 75@1st/2500 or 2nd/2500, 100@3rd/2500?

Would like to be 'incognito' as possible. Haven't made any decisions whether to use edelbrock manifold/carb from 3.9, but would have to install c-hood for height - f.i. a possibility.

Looking forward to you breaking 10 - thanks for taking the 'hit' for us!

Dont forget while the tyres are spinning you aren't breaking shafts!!! Get stickys and things change...

Tony Andrews wrote:Thanks for the response Perry. I figured you'd be the one as you seem to be the resident go to nos guy.

I'm running an lt77 5-speed and 3.07 dana posi. Obviously, traction will always be a problem - especially with street tires. The stock cam appears to be fairly decent for this application - short exhaust duration/wide lca. With peak tq at approx. 3000 rpms, what are you're recommendations regarding progressions - 50@1st/1500, 75@1st/2500 or 2nd/2500, 100@3rd/2500?

Would like to be 'incognito' as possible. Haven't made any decisions whether to use edelbrock manifold/carb from 3.9, but would have to install c-hood for height - f.i. a possibility.

Looking forward to you breaking 10 - thanks for taking the 'hit' for us!

The best thing would be to use a digital programmable controller with basic functions of Start power, Build time and final power. The controller will also need to have a Reset function. The reset function gives you the option to reset back to start power each time you lift off for a gear shift, or you can set it to start building from where you left off in the power build / ramp time.

For your gearbox I would say a good safe start point would be to fit 50hp jets. Set the start power to 25% (12.5hp) with a build time of say 4 seconds. This will give you gentle power at the start of each shift. Then its down to understanding how your car behaves and adjusting / increasing nitrous power from there.

This is the sort of controller I use. But I have my reset turned off. As I'm automatic my foot does not lift off until I cross the line or things go wrong. I set mine to 100hp off the line with a 2.2 second build to 240hp. This means I have pull power as I shift to 2nd gear.

If you want to get funky you could buy a top notch controller so you can programme the power for each gear individually, set the min rpm that the nitrous activates at, set an upper rpm limit to cut the nitrous before you hit a limiter, dial in some retard automatically.

You have a few options for a stealth install up to around 150hp.
Wizards do the super stud. I'm not sure if NOS still do the sneaky pete?? Both of these fit inside a 14" air filter on top of the carb.

Make sure you buy solenoids that are good for pulsing!

Perry

Better late than never to respond. Atlantic mid-coast has been pounded by snow lately - server down for several days and then power cord for laptop decides to break - had to make a quick purchase on ebay Monday - just powered up.

Thanks again Perry - good stuff!

No probs Tony!
Ask all the questions you want to

Funnily enough, the Wizard of nos himself is at present in the USA to try one of his new kits on a pro mod car. This will be a huge event in our little UK Nitrous kit circle.

Can you show me a picture of the Dana axle please??

I'm still running my stock MGB V8 Salisbury 3.07:1 rear end. Its a good strong unit and it has no trouble getting wheels in the air so far. But the locker I have fitted consists of several arc welding rods
The Phantom Grip I was using got damaged when the diff pin let go and trashed all but the crown wheel, pinion and cage. That was a lucky escape. I called Quaiffe and asked for a locker that would handle 600 ft/lbs and they said they would not guarantee it??

So I'm stuck with a home brew spool at the moment.

Regards
Perry

How's this:

http://www.britishv8.org/Articles/Dana44Axle.htm

"let go and trashed all but the crown wheel, pinion and cage"

Damn lucky - like tryin to hit a rack of billiard balls and missin the rack!

So how's the plan coming along Tony?