Newbie, Motor Swaps.
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Newbie, Motor Swaps.
Hello everyone,
I have just purchased a 86 iroc 305 tpi. It is bone stock and had low milage((70k)) The 305 feels ok, but i think that the 350 would feel better. I dont want to do a ls swap. I kinda wanna keep it somwhat original. I was wondering if someone could give me rough power output and 1/4 times on the 305/350/383 I was thinking of going 383, i hear it is very nice. Can you go larger then 383? Like the title says, i am new at this, so any info can help. I always liked Irocs, now i have one and dont want to get punked by some hopped up ricers. Also please keep in mind, im not looking to spend like 15km this would be over the span of about a year, to do things right.
Thanks in advance.
Josh
I have just purchased a 86 iroc 305 tpi. It is bone stock and had low milage((70k)) The 305 feels ok, but i think that the 350 would feel better. I dont want to do a ls swap. I kinda wanna keep it somwhat original. I was wondering if someone could give me rough power output and 1/4 times on the 305/350/383 I was thinking of going 383, i hear it is very nice. Can you go larger then 383? Like the title says, i am new at this, so any info can help. I always liked Irocs, now i have one and dont want to get punked by some hopped up ricers. Also please keep in mind, im not looking to spend like 15km this would be over the span of about a year, to do things right.
Thanks in advance.
Josh
Joined: Mar 2000
Posts: 43,187
Likes: 46
From: Littleton, CO USA
Car: 82 Berlinetta/57 Bel Air
Engine: L92/LQ4 (both w/4" stroke)
Transmission: 4L80E/4L80E
Axle/Gears: 12B-3.73/9"-3.89
Welcome aboard thirdgen.org.
The 3rd gen 350 TPI horsepower king was a grand 245 net flywheel horsepower, vs. your current 190 net flywheel horsepower. Now, other than the 45 cubic inch increase, what else did they change, you ask?
A lot.
In 1987, the now-available 350 TPI put out 225 HP. BUT, you could get a 305 TPI that put out 215 HP. So, truth is, you could probably get your 305 to put out 245 net flywheel horsepower, if you were also willing to change a lot of things. So, what would you change? The TPI base, runners, and injectors, as well as porting the plenum, and then do cam and exhaust changes. Then start doing your own PROM tuning. Now a larger engine is no big deal, considering all you've had to do already, so you'll just bump up the difference in output proportional to the displacement increase. You'd probably also conclude at this point that your current MAF system has limitations that would lead you to go to a speed density system, which is no big deal since you're changing out most everything in the TPI, anyway.
But, in order to go with a 383, you're looking at a complete induction change, to something like Super Ram or Miniram. TPI is just more restrictive than you want to subject a 383 to.
Regardless, in case you haven't figured it out yet, you're looking at a pretty good piece of that $15k you don't want to spend. At least a third of it.
The 3rd gen 350 TPI horsepower king was a grand 245 net flywheel horsepower, vs. your current 190 net flywheel horsepower. Now, other than the 45 cubic inch increase, what else did they change, you ask?
A lot.
In 1987, the now-available 350 TPI put out 225 HP. BUT, you could get a 305 TPI that put out 215 HP. So, truth is, you could probably get your 305 to put out 245 net flywheel horsepower, if you were also willing to change a lot of things. So, what would you change? The TPI base, runners, and injectors, as well as porting the plenum, and then do cam and exhaust changes. Then start doing your own PROM tuning. Now a larger engine is no big deal, considering all you've had to do already, so you'll just bump up the difference in output proportional to the displacement increase. You'd probably also conclude at this point that your current MAF system has limitations that would lead you to go to a speed density system, which is no big deal since you're changing out most everything in the TPI, anyway.
But, in order to go with a 383, you're looking at a complete induction change, to something like Super Ram or Miniram. TPI is just more restrictive than you want to subject a 383 to.
Regardless, in case you haven't figured it out yet, you're looking at a pretty good piece of that $15k you don't want to spend. At least a third of it.
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