TBI TPI Swap power gain worth the trouble?
#1
TBI TPI Swap power gain worth the trouble?
Just curious,
What kind of HP will I gain on my 305 if I change the TBI to TPI?
Another thought is to change the crank and get it to a 350 (345), or so I have heard that this is a possibility.
My engine is still being looked up to find out how it was setup.
I already have the complete TPI setup off of a 91 Z.
Thanks
Rob
92 RS
305
Manual
What kind of HP will I gain on my 305 if I change the TBI to TPI?
Another thought is to change the crank and get it to a 350 (345), or so I have heard that this is a possibility.
My engine is still being looked up to find out how it was setup.
I already have the complete TPI setup off of a 91 Z.
Thanks
Rob
92 RS
305
Manual
#2
The crank size is the same for 305's and 350's. Its the bore size that is different, and the 305 and 350 blocks are different. You cannot turn a 305 into a 350. Your option is to remove the 305 block and replace it with a 350 one.
My dad converted his 305 TBI over to TPI, and he gained 17 horsepower and 70 torque at the rear wheels. Then he swapped in a 350 engine and has never been happier. Yes its very much worth it to dump TBI and switch to TPI or better fuel injection.
My dad converted his 305 TBI over to TPI, and he gained 17 horsepower and 70 torque at the rear wheels. Then he swapped in a 350 engine and has never been happier. Yes its very much worth it to dump TBI and switch to TPI or better fuel injection.
#3
Senior Member
![](https://www.thirdgen.org/forums/images/ranks/tgo10.gif)
Join Date: Jul 2003
Location: P'cola
Posts: 646
Likes: 0
Received 0 Likes
on
0 Posts
Car: 1991 Z28 Camaro
Engine: L98
Transmission: 700R4 that will magically turn into a 6 speed one day.
stuff needed
Hey, sorry to go off topic, but I am wanting to do the exact same swap, and I am just wondering if you have a list of everything I would need to do the entire swap from TBI to TPI. Would I need and sensors and what kind of ecm, any info would be great. I have the L03 right now and would love the better power and economy the TPI has to offer.
Thanks
Lc
Thanks
Lc
#4
Re: stuff needed
Originally posted by 305RSlc
Hey, sorry to go off topic, but I am wanting to do the exact same swap, and I am just wondering if you have a list of everything I would need to do the entire swap from TBI to TPI. Would I need and sensors and what kind of ecm, any info would be great. I have the L03 right now and would love the better power and economy the TPI has to offer.
Thanks
Lc
Hey, sorry to go off topic, but I am wanting to do the exact same swap, and I am just wondering if you have a list of everything I would need to do the entire swap from TBI to TPI. Would I need and sensors and what kind of ecm, any info would be great. I have the L03 right now and would love the better power and economy the TPI has to offer.
Thanks
Lc
#5
TGO Supporter/Moderator
![](https://www.thirdgen.org/forums/images/ranks/tgo10.gif)
iTrader: (12)
Join Date: Jul 1999
Location: SALEM, NH
Posts: 11,741
Likes: 0
Received 89 Likes
on
75 Posts
Car: '88 Formula, '94 Corvette, '95 Bird
Engine: LC9, 355" LT1, LT1
Transmission: T5, Zf6, 4L60E
Axle/Gears: 3.42, Dana44 3.45, 3.23
Before you spedn a lot of dough on a TPI unit you m ight wanna look at the holley stealth ram.
-- Joe
-- Joe
#6
Supreme Member
Here you go. Can't argue with actual dyno graphs. Looks like to me you should concentrate on exhaust before anything else. Maybe do the ultimate tbi mods and you will be a lot more happier than if you switched to tpi.
http://bitchincamaro.no-ip.com/dyno.html
http://bitchincamaro.no-ip.com/dyno.html
#7
I think the TPI swap is still valid. And a stock 350 doesn't gain a whole lot with an aftermarket unit like the Stealth Ram. It's when you really start getting into headwork and cam that the change is worthwhile.
Even if he installs the TPI system now. He can still upgrade to the Stealth Ram later. Just change the intake, plenum and runners.
TPI system's are pretty inexpensive all things considered. If you already own the TPI hardware it's definatley worth while.
I think it's worth it. Go for it.
Even if he installs the TPI system now. He can still upgrade to the Stealth Ram later. Just change the intake, plenum and runners.
TPI system's are pretty inexpensive all things considered. If you already own the TPI hardware it's definatley worth while.
I think it's worth it. Go for it.
Last edited by 87WS6; 08-12-2003 at 03:11 PM.
Trending Topics
#8
Supreme Member
![](https://www.thirdgen.org/forums/images/ranks/tgo10.gif)
Join Date: Apr 2003
Location: B'ville, WV
Posts: 1,781
Likes: 0
Received 0 Likes
on
0 Posts
Car: 2002 Formula Firebird
Engine: LS1
Transmission: 4l60e
Axle/Gears: 3.23
I remember someone on the boards saying there dad had a 91 (i think) lo3 car. He gained 17hp and 70lbs torque at the wheels from just a TPI swap and nothing else.
If he sees this post im sure he will confirm this.
If he sees this post im sure he will confirm this.
#9
Originally posted by 88Camaro350
I remember someone on the boards saying their dad had a 91 (i think) lo3 car. He gained 17hp and 70lbs torque at the wheels from just a TPI swap and nothing else.
If he sees this post im sure he will confirm this.
I remember someone on the boards saying their dad had a 91 (i think) lo3 car. He gained 17hp and 70lbs torque at the wheels from just a TPI swap and nothing else.
If he sees this post im sure he will confirm this.
![Big Grin](https://www.thirdgen.org/forums/images/smilies/biggrin.gif)
#10
Thanks all.
For those that have done this,.. is it straight forward?
I have spoke with some companys that sell TPI's setup's and they say it is a straight swap.
I spoke with Howell and they say to convert the TBI harness, so that all of my guages work.
I thought that the wiring was all the same (under the dash) except the fuel injector part.
I have the harness,.. straight forward?
Rob
For those that have done this,.. is it straight forward?
I have spoke with some companys that sell TPI's setup's and they say it is a straight swap.
I spoke with Howell and they say to convert the TBI harness, so that all of my guages work.
I thought that the wiring was all the same (under the dash) except the fuel injector part.
I have the harness,.. straight forward?
Rob
#11
Member
Join Date: Sep 2000
Location: Granite City, IL, USA
Posts: 264
Likes: 0
Received 0 Likes
on
0 Posts
TBI TPI Swap power gain worth the trouble?
Kyle
#12
Supreme Member
Originally posted by 25THRSS
Here you go. Can't argue with actual dyno graphs. Looks like to me you should concentrate on exhaust before anything else. Maybe do the ultimate tbi mods and you will be a lot more happier than if you switched to tpi.
http://bitchincamaro.no-ip.com/dyno.html
Here you go. Can't argue with actual dyno graphs. Looks like to me you should concentrate on exhaust before anything else. Maybe do the ultimate tbi mods and you will be a lot more happier than if you switched to tpi.
http://bitchincamaro.no-ip.com/dyno.html
#14
Moderator
![](https://www.thirdgen.org/forums/images/ranks/tgo10.gif)
Join Date: Mar 2001
Location: Doghouse ······································ Car: 1989 Formula 350 Vert Engine: 350 L98 Transmission: 700R4 Axle/Gears: B&W 3.27
Posts: 14,235
Received 164 Likes
on
119 Posts
Car: 87 Formula T-Top, 87 Formula HT
Engine: 5.1L TPI, 5.0L TPI
Transmission: 700R4, M5
Axle/Gears: Sag 3.73, B&W 3.45
I did a little different conversion I went from an LG4 to the TPI on my 87 Formula, and I really think it was worth it.
I remember swapping the following:
engine wire harness
dash wire harness (I think you can skip this one with TPI)
intake runners etc.
Swapped sides with the Battery
Ran the fuel lines
Dropped the axel, put in the TPI fuel pump in tank.
I really did not notice a big gain with the HP end, not until I got into programming, but my fuel milage wendt from 17mpg to 23mpg![Big Grin](https://www.thirdgen.org/forums/images/smilies/biggrin.gif)
John
I remember swapping the following:
engine wire harness
dash wire harness (I think you can skip this one with TPI)
intake runners etc.
Swapped sides with the Battery
Ran the fuel lines
Dropped the axel, put in the TPI fuel pump in tank.
I really did not notice a big gain with the HP end, not until I got into programming, but my fuel milage wendt from 17mpg to 23mpg
![Big Grin](https://www.thirdgen.org/forums/images/smilies/biggrin.gif)
John
#15
Member
![](https://www.thirdgen.org/forums/images/ranks/tgo10.gif)
Join Date: Sep 2002
Location: Duluth, Ga
Posts: 330
Likes: 0
Received 1 Like
on
1 Post
Car: 91 RS
Engine: 305 TPI
Transmission: T56
Axle/Gears: Auburn Pro / 3.42
If you want more hp full exhaust is the way to go as far as first mods. If you already have a tpi setup go ahead and do it. I love the torque and the car runs much smoother. I dont regreat doing the swap though.
#16
Moderator
![](https://www.thirdgen.org/forums/images/ranks/tgo10.gif)
Join Date: Mar 2001
Location: Doghouse ······································ Car: 1989 Formula 350 Vert Engine: 350 L98 Transmission: 700R4 Axle/Gears: B&W 3.27
Posts: 14,235
Received 164 Likes
on
119 Posts
Car: 87 Formula T-Top, 87 Formula HT
Engine: 5.1L TPI, 5.0L TPI
Transmission: 700R4, M5
Axle/Gears: Sag 3.73, B&W 3.45
One advantage you will get for doing a swap... is experience. well worth it. I am MUCH more comfortable working on computer controlled GM vehicles. I would be that once you get done, you will be more knowledgable than many if not most of the other folks here. ![Wink](https://www.thirdgen.org/forums/images/smilies/wink.gif)
John
![Wink](https://www.thirdgen.org/forums/images/smilies/wink.gif)
John
Thread
Thread Starter
Forum
Replies
Last Post
carborated, changed, conversion, engine, fuel, gain, gains, hp, injection, performance, power, swap, tbi, tpi, worth