Ok guys who has been able to get at least 350hp from their tbi (GM tbi or Holley 670 with a factory ecm) No bench racing, no guessing & no NOS, motor only. Has anyone done it? Do you have dyno #'s or track times to back it up? Also anybody broke in the 12's (same rules) at all? If so let's here it.

Later,
Mike

 

I am going to cheat a little. I have a factory ECM with a Moates G2 adapter and flash chip in it, with lots of custom work. I have had several engines that have made 300+ HP N/A at the crank. Right now I am pretty darn close maybe even a little more, I have an honest 272 RWHP through the mufflers from a 305 but has a 454 TBI assembly. Sans the restriction of the mufflers it came to an even 300 RWHP @ 6,300 RPM(to get that RPM level without going static takes 68 lb/hr injectors @ 32 PSI) it also made 325 ft/lbs of torque at the pavement. My old 355 was making 279 RWHP and 345 ft/lbs through a rochestor 220 TBI with Ultimate TBI mods. A different 305 combo of mine was making 245 RWHP/340 ft/lbs. Finally a 355/ Ported 601 HO 305 Head/ Mellings MTC1 cammed beast was making 255 RWHP and nearly 360 ft/lbs. No Nitrous on any of my engines.

I have a timeslip for a an 1/8 mile of 9.89 @ 69.08 with a 2.198 second 60' time in a 5,300 lbs G-series van with a 312 (.040 over 305) TBI in it. That is roughly a low-mid 15 second 1/4 mile. Bench racing as to what it would do in a 3,400 lbs F-body, with the old 355 had me darn close to the 12s, IIRC. Kdrolt may remember more, since he ran the simulations for the comparisons. Look up my old times in my post about porting 193 heads. I ran a 15.6 second 1/4 in a G20 conversion van with a 3.08 gear.

My Specs & Timeslip



The left lane is a 2002 VW Beetle 2.0-4cyl/Auto that thought he would beat me. I can say I left $50.00 better though.

 

with old cam and xram it was 222 HP at wheels. maybe 290 at motor?. that came at 5000 rpms and A/F 12.00/1 at 90 deg F and 90% humidity. the new cam is rated at 5800 rpms. the new manifold rated up to 6000 rpms so call that a draw. running 13.3/1(lean i know) last WOT pass. car is noticably faster by SOTP. fuel mileage is much worse so maybe that a good thing? will try to get to dyno yet this fall. no time to do so.

 

Fast355, that kind of power at the wheels from a 305 is pretty good. I want 300RWHP if possible and I'm just trying to get an idea what it will take, using more more motor 350 or 383.

 

I will say one thing though RPMs are not your friend on a TBI setup. It is tough to tune a little high RPM screamer such as this, without going static on the injectors and running TOO rich at idle. I have the opinon that for the same power level the bigger engine is going to be easier to tune. In other-words it is easier to tune a 300 RWHP 350 than a 300 RWHP 305.

 

<== Not even close