qwiketz

I had great results with ultra flow welded 2.5" mufflers on my mustang. Flow great and sound great.

LT1inaMGB

I'm going to replace the Flowmaster with a Dynomax Ultra Flo and see what that does. I'm changing the cam right now to one with 10* less intake duration and a 114* LSA to get better 6th gear cruising performance so it will be interesting to see if the peak hp rpm increases despite having a milder cam. I'll let you know after I get it dyno'd.

LT1inaMGB

I recently changed out the cam in my car for a milder one to get better freeway manners in 6th gear. This cam has 10 degrees less intake duration and a wider lobe separation angle of 114 degrees which definitely improved the performance at low rpm (1400-1700) eliminating the need to down shift when traffic slowed. At the same time I put a larger pulley on the blower to reduce the boost and changed out the Flowmaster muffler for a Dynomax. The old cam made massive torque (543 ft lbs at the rear wheels) and the horsepower was 450 but at only 4800 and then it dropped off rapidly. I had a 50 series Flowmaster on it and switched it out for the Dynomax Ultra Flow Welded. The Flowmaster flowed only 53% of an open pipe whereas the Dynomax was 101%. With the smaller cam you would expect the horsepower be lower and to peak at a lower rpm but it actually raised the peak almost 1000 rpm peaking at 466 rear wheel hp at 5750 rpm (that's 536 flywheel hp). What a difference a muffler makes! After this post the name "Flowmaster" will be forever stricken from my vocabulary.

Before the horsepower and torque peaks the new curves were flatter and lower as I expected but it still makes over 300 ft lbs at 2500 rpm and 425 ft lbs at 3000 rpm and it stays over 400 ft lbs past 6000 rpm (peak is 479 ft lbs at 4300 rpm). All the new numbers were with the water/methanol injection turned off and the old ones were with it turned on so they will probably be closer with the system on. So am I disappointed with the lower performance now? It still has plenty of power to scare me and I still need to be sure to have it pointed straight ahead when the boost comes on. What is nicer is the normal driving and I think it will be much easier to control in autocrosses, I just need to control the acceleration rate by shifting early.

I am going to keep the old cam because if I build another engine with forged internals ( I have a stock shortblock with cast pistons and 11:1 compression now) I would love to see what it would do with the less restrictive exhaust. My guess is well over 500 rwhp and close to 600 rwtq and I could regain some of the low end performance with a set of Rhoads lifters http://www.rhoadslifters.com/Pages/Articles.html The engine just won't take that kind of hp now.

BrianCunningham

Mine is pretty cammy as well

Look forward to your Rhoads lifter report

LT1inaMGB

Hopefully, that report won't be coming for a while. I'm only going to do it if I have to strengthen the internals (forged pistons, good rods, etc) and that will mean that I have broken the stock pistons. I want the engine to last for at least another year or more so I have a chance to finish up the car. I'm happy with the freeway manners now but it has noticeably less midrange than before (down about 60 ft lbs at 4000 rpm) but that actually makes the car easier to drive in an autocross environment, before I had to be careful to have the car pointed straight ahead when the boost kicked in. The car still accelerates like a banshee because of the increased hp and extended rpm range.

illenema

What does the Mgb Weigh stock

LT1inaMGB

A stock '66 MGB weighs just over 2100 lbs but mine is 2700 lbs. 535 fwhp moves it along very well. It has a better power/weight ratio than a new Z06 Corvette.

Tom400CFI

Cool. Now fab up some headers and see what happens.

Tom400CFI

Wanted to bump this thread b/c:
1. I think that this car is WICKED
2. He's got a vid of it out there now! Check it out!

95wht6spd

Yep, beautiful car, and great work. I watched the video on Youtube a few days ago, and it seemed familiar, I had totally forgotten about this thread.
It is more C4 than MG.

70T/A400

This girl makes great videos. Love her enthusiasm for cars, trucks, Uni-Mogs-anything with wheels and internal combustion.

383vett

Nice car and build.