How much horsepower...?

2001 was a very good year for the LS1.
The A4 (auto) version generally puts less power to the ground than the M6 (6 speed) due to more parasitic drivetrain loss. However, they are the better choice for a racer because they are far more consistent and better to get traction. The M6 is fun to drive and puts tons of power down, but that makes them unreliable to race.
An A4 with a stall converter, muffler, and air cleaner will bracket race like a dream.
Also, the best gear you could get in an A4 was 3.28.
M6 came with a 3.42... Aluminum driveshaft standard too.

If you ever get a chance, drive an M6 car.

Fwiw, NEVER run an LS1 car from a roll! They will wax just about anything from a roll. They have traction and torque issues from a stand still unless they have been modded. A4 cars are very lazy off the line until they have a converter, M6 cars just blow the tires loose from a stand still. Mine would blow the tires loose from a roll at just about any speed.

 

You are surely running 200 rwhp...
You would also surely benefit from a light stall converter.
Would get you into your power band super fast. Stock converters are very lazy.
200 rwhp is about 250 fwhp with a C4, does that sound about right?
I might throw it on the computer dyno for something to do...

 

I don't know...sounds about right, I guess.

I have a supercharged V6 Bonneville (around 150HP)and a HUGE Hemi Dodge (360 HP plus all kinds of weight, maybe 4000 lbs+?) truck to compare it to. I always thought the truck was fast, with it's 7000 redline and 4.11 gears. Then I "raced" my wife off the line at a red light and it wasn't even fair, left the truck like I was racing a Honda (non-riced version)

I then started to compare to the cars I raced at the track for estimates. The closest match was a 2001 or so mustang. He beat me, but it was almost a tie...less than half a car length. So I found the stock weight of his car and stock HP, then figured out my weight and calculated the HP (don't remember what the numbers came out to)...But since then, I have swapped to GT40P heads, deeply ported single plane intake, and headers...I have been trying to catch that guy again at the track. No contest next time

 

I've eaten many LS1 cars from a dig and a roll, all with my last little 306. :evilsmile I plan on doing the same with a Maverick too.

 

Same here. It's even more fun when you tell the guy that he got his a** handed to him by a 2.3L ranger engine.

 

The best I can tell, 275hp - 300hp in a Maverick should be plenty quick. I am estimating right around that mark with my current motor. I would like to get some different heads and compare. Currently running 289 heads. I have thought about a set of the GT-40P heads. Do the GT-40P head require different headers?

 

GT40P heads use the same headers...it is just more difficult to reach the spark plugs.

MUCH better flow. I cannot say MUCH too much when in reference to these heads. These are the best $300 I ever spent, by a long shot. Despite the hassle I had "re-learning" how to change spark plugs... :16suspect

 

scooper77515 will answer that I am sure.
He has P heads on his 302.
The spark plugs are relocated on the P heads, so the headers are a bit of an issue. I mocked up a set once and determined they weren't for me. Scooper has seemed to figure them out though.

You can get just as much performance from a set of 69-73 351w heads without any header issues. The P heads may also require pedestal rockers too, I don't recall.

289 heads definately leave some to be desired. They make good compression, but the ports and valves lack. I was only able to get around 275-300 hp out of my 289 heads, and that was with port work and Chebbie valves. They weren't weak heads, but they were to their limit.

Early W heads worked to their limit are better than some aftermarket heads.
And you don't just have to run 1.94/1.60 valves either... they already have 1.85/1.54 stock. You can get the labor done and buy new valves, but you end up spending a good chunk of what you would for some aluminum heads.
Aluminum allows another point of compression, just have to make sure you get a good flowing brand.

Dave

Edit: Scooper 'scooped' me!

 

Yoov bin SCOOPED!!!

I know the P heads are not the top of the line, but admit it, where else are you going to get THAT much improved flow from only $300???

No pedestals. I literally bought them from a junk yard, and bolted them on. They had the valves, springs, and lifters from the stock Explorer. I just hosed them down at the local pressure washer car wash, and bolted them on.

I will argue about the flow compared to the 351 heads...when I was researching flow data, I found that they WAY outflow the 351s. Do a search, I think someone posted a chart with a variety of heads with flow data graphed out. I had acces to free 351 heads and went P due to the significant increase in flow.

But, you do lose a little compression with them.

Cool thing is my engine machinist routinely builds 347 strokers with non-P GT40s, so he knows the ins-and-outs of that setup. The Ps will only improve on this setup when I have it rebuilt!

 

try this website

http://www.allfordmustangs.com//Detailed/630.shtml

the stock 69 351 4bl is not as good as the 40Ps

 

Yeah, that is the chart I was thinking of...

Really informative site. It was the exhaust flow that sold me on the Ps. The intake is just a little better than the 351 heads, but I was always under the impression that it was the exhaust on our cars that was constricting our power.

I also did a mild porting on the exhaust ports, just knocking off the smog bump, and cleaning and polishing the outer 2/3 of the ports. A little widening of the ports, but not quite gasket matching. When I do my rebuild, I might do the bigger valves, roller rockers, etc. But at that point, it will be a juggling act between the money spent improving these heads or buying aluminum...AFRs, most likely.

Another thing about the Ps (Ratio was correct about me having something to say , I ought to become a spokesperson for the Ps, kind of like Jared from Subway ). The reason the spark plugs are so hard to get at with headers installed is because they are placed into the center of the combustion chamber, almost like the hemi heads. They stick out at a 10 degree angle, compared to the 30 or 35 degrees on most heads (these are off-the-cuff figures, estimates). This means the spark plugs stick almost straight out of the head, not sticking out an angle. This puts the tip of the plug almost touching the center of each header tube on one side of the car. On the other side, you can very easily get to all the plugs because the tubes flip out the other way openly exposing the plugs.

I have pics posted at
http://mmb.maverick.to/showthread.php?t=18214&highlight=GT40P