According to Scoggins Dickey, just adding Vortec heads and their Vortec TPI base to an L98 engine will result in 300 hp using the stock computer. I'd like to get 325-350 flywheel hp(and no more) with the best possible gas mileage and am wondering which of the cams below might do that using the original computer(my husband wants to use a mega-squirt computer but I don't see him having the time to set it up).

The motor is a flat tappet 79 L82 350, 10:1 compression Vortec/TPI with AS&M large tube runners. Scoggins Dickey says other modifications on their otherwise stock L98 such as camshafts, rocker arms and injectors produced as much as 375hp with the stock computer and throttle body. One of those included an LT4 Hotcam but seeing as Vortec heads max out flow at about .500 lift I think the extra lift of their 1.6 ratio hotcam was wasted and a milder cam would do just as well.

My goals for the motor might conflict a bit, I have a 5 speed and 3.70 rearend. The first gear is 3.37 ratio so I'm hoping to rev to 6000 rpm and not have the power drop off drastically. The fifth gear is .67 overdrive so I will be cruising at 2000 rpm at 62.5 mph. The cams I'm looking at (all designed for TPI) are:

Crane 2032: 214/220 duration, .452/.465 lift, 112 LSA, operating range 1800-5800 rpm

Comp cams 266HR-14: 210/220 duration, .500/.510 lift, 114 LSA, operating range 1400-5400 rpm

Comp cams XR269HR: 218/224 duration, .495/.503 lift, 112 LSA, operating range 1500-5500

Lunati 10120701 (flat tappet): 212/219 duration, .454/.468 lift, 112 LSA, operating range 1000-5500

Third Gen member Mike Crews
https://www.thirdgen.org/forums/afte...-tpi-dyno.html
used the Comp Cams XR269HR in his TPI/Vortec 383 with AS&M runners and produced 303 rear wheel hp at 5100 rpm and said he was really impressed with the gas mileage. He said the horsepower dropped off after that rpm but not much and it pulled all the way to 6000 rpm. Assuming a 20% drivetrain loss I work out that my 350 with a similar combo should produce 346 flywheel hp. Would I do almost as well with one of the other cams but get better mileage? What do you think?

 

i like the crane 2032. i have it in my 305 with 1.6 ratio rockers, but i run stock style world product s/r torquer heads and edelbrock tpi base and accel runners.

not sure what the 350 will put out with that combo

why the need to rev to 6k? the tpi isn't made for that

 

I realize tpi isn't ideally suited to high rpm but I hope to coerce it to do so. The reason is my 3.70 rearend and 3.37 first gear which will result in 36 mph in first gear at 6000 rpm. I don't want to drop the clutch and have to shift out of first 1 second later at 25 mph. With those gears I really don't need the low speed torque TPI is known for although I do need it to be efficient for crusing at 2000 rpm.

 

ttt

 

Given the choices presented I would go for the comp.

 

Getting the TPI to 6000 is going to be interesting. My Vortec headed HSR with LT4 hot cam slowly pulls to 6000 from 5500 with 3.90 gears.

Out of those cams I'd pick the comp, however.

 

214-220,.510-.510at110

 

I wouldnt recommend a lift of over.475 on stock vortec heads. I made around 320-340hp with stock vortec heads and a 218 218 hydraulic flat tappet cam with 465 lift and forged pistons. Headers and a carb.

 

Something is wrong with your tune or exhaust setup. My long tube runner TPI Vortec setup would pull to so hard up top that my transmission would not shift quickly enough to keep it from bouncing off the 6,200 rpm rev-limiter on the 1-2 shift.

It was a 355, .030" over 350 with flattop pistons, 10.5:1 compression ratio, ported/milled 906 vortec heads with 2.05/1.60" valves, a reed custom grind
260/264* @ .008, 208/212 @ .050, .480/.507" lift w 1.6:1 rockers, 112* LSA, 108* ICL. running an edelbrock 3817 base that had been ported, and a set of AS&M long tube runners, doug Thorley tri-y headers and 2.5" dual exhaust. Run by a 7730 tuned by me on SAUJPv4

 

Fast355- to be fair to the rest of us- your setup is likely tuned to the Nth degree.
One thing that has never been explained to my satisfaction is the difference between single and dual pattern cam as it relates to a street set up, what is the deciding factor in the head vs exhaust. I`m using AFR vortecs, I`ve read that if the head has at least 85% I vs E your OK with single pattern that will give more torque, I`ve full single exhaust 3in with TES headers and Y-pipe.

 

Which one? I posted two comp cams.

 

Sounds interesting. I could modify the Vortec heads but it would be a bonus if I could use a cam that doesn't require that. How did you get that 320-340 hp estimate?

 

What do you run for a cam?

 

If you don't modify heads looks like your choices are narrowed down to crane or lunati. They both look comparable to one another.

 

I'm open to modifying the heads but if I can achieve my goals with a cam that doesn't require that its a bonus.

 

Reed custom grind
260/264* @ .008, 208/212 @ .050, .480/.507" lift w 1.6:1 rockers, 112* LSA, 108* ICL

I posted my engine specs in my original post.

Long tube AS&M runners with a ported 3817 base.

 

Yes it was tuned to the Nth degree.....When you don't have a pile of cash to throw at it, but have tuning knowledge and some spare time, you extract all the power out of a given combination of parts.

Case in point.....My 2012 Titan was factory rated a 317 HP/385 ft/lbs of torque at the flywheel. I put a 4" CAI on it, ported the throttle body, removed the throttle body gasket screen, bypassed the coolant to the throttle body, removed the resonators and in their place put a 2.5" mandrel bent exhaust. I then tuned it for E85 and made 296 RWHP/388 RWTQ on a Mustang dyno that reads 10% lower than ANY Dynojet. Went 13.9/14.0s @ 96-98 mph, despite weighing 5,300+ lbs, having an open differential and heavy 305/50R20s on each corner. I was able to tweak the tune to get a fairly consistent 1.99-2.01s 60' in good weather. So a lot of it is working to get the best out of the combination you have.

 

I don't know how I missed that. Thanks very much. Very interesting.

 

Because I added it after you asked, to make it easier for others to see that might want to know the same thing.

 

My most current 350 is running a marine intake from a 350 vortec powered boat. Aluminum edelbrock ETec heads and a custom grind comp cam. Makes 374 RWHP through a locked 4L80E in a 2nd gear pull and 9.5" GM corporate 14-bolt rear end. Was still making more than 350 RWHP @ 6,500. 325 ft/lbs @ 2,300 rpm.