I realize that TPI is an MPFI system but I'm wanting to whether I should go with a conversion(like edelbrocks)or aftermarket TPI. Which would be cheaper? Make more power? thanx!

------------------
Pretty damn smart with cars for 17!
91 Camaro RS, 305 TBI
No mods yet...Hopefully:
Convert to dual-cat with headers and Borla catback exhaust.
Edelbrock MPFI system.
RAM air hood & Z28 wing.
Z28 cam.
ABS system.
Positraction rearend with rear disc brakes.
Rebuilt front and rearend suspension with polygraphite bushings.
Strutbrace.
Rollbar.

 

it is always cheaper to work with what you got. with any type of port injection you could prolly expect more top end power, but they always sacrifice torque. torque is the kick in the pants you get when you punch it at a stop light.

lata
tim

------------------
91 Camaro RS-LO3,Auto.
14.301 @ 94.39mph
The car is going street strip for next season. 13's here i come!!!!!
Edlebrock TES Headers, Cat Eliminator Pipe, Borla Adjustable Cat Back,Marche Pulleys, HyperTech Chip,Transgo Shift Kit,B&M Convertor(2000stall),Steve Spohn Rear Rig( all rod ends), Poly Front Bushings,Ported TB, 350 Injectors, Edlebrock Performer TBI Intake, Performer Heads, 1.6 Roller Tipped Rockers
http://www.mycar.net/mafb/registry/detail.cfm?id=299

 

always. and i mean always remember, torque is the measure number. horsepower is the number figured from torque at rpm. TORQUE IS THE REAL NUMBER. THE IMPORTANT ONE WHEN DEFINING POWER!!!!

 

Uhh... what do you mean you lose torque when you convert to TPI? Thats BS. You GAIN torque! My dad just put a TPI intake on his 92 Camaro RS TBI engine and made all the necessary changes for the computer and wire harness, and he says his TPI rocks!

------------------
West Coast GM Shootout 2001!
1991 Camaro Z28
5.7L 5-Speed (originally 305)
13.25 @ 107.18 MPH
Southern California
Member: SoCal 3rd Gen F-Bodies
Webmaster: SoCal F-Bodies
-=ICON Motorsports=-

 

TPI has more low end torque than TBI. Top end is where TPI suffers.

------------------
'68 Camaro - Vortec 350
'85 Camaro Z28 - 305 TPI - FOR SALE
'91 Camaro RS - 305 TBI

 

i think that is different with CFI. i peek my torque right now at around 2200 rpms

------------------
RED82TA5.7L
this car has a bad tranny untill middle of January 2001(im crying inside) soon to be 350 Raptor TH350 from http://www.transmissioncenter.net
1982 Pontiac Trans Am
Cross-Fire Injected 5.7l V8
Eldebrock Headers, 3" Hooker Cat-Back, duel outlet with quad tips.
Mods: 1.6 Proform Roller Rockers, electric fan, Corvette 5.7L computer chip, K&Ns.
Audio: JVC Kameleon CD deck, Jenson 4x6 front, Eclipes 6x9 rear, 2 10" mTx T4000 powered by a mTx 200watt amp.
Black Powder Coated 1990 16x8 Formula Wheels with 245/50/ZR16 Perelli P7000.
For Pictures go to
http://members.theglobe.com/RED82TA57L/mycar/


A cool Trans Am site with Message Boards http://www.transamgta.com

 

why do you want to convert to tpi? thats the first question, Next is , can you get the performance from a TBI as good or better than a tpi , definately!! The whole motor is the power package

 

second re, the power package is te whole motor. another thing is , ask yourself were in the RPM range you want to mke power at and if youll be in the power range , as in ( daily driving racing and so forth).
you know, most TPI setups are built to make power from 0 to 5000RPM, on average and if you dont care to pull higher RPM then TPI isthe way to go (long intake runners make great torque) but like I said , A TBI setup built right will do the same job with higher rpm capability and less MONEY>>> good luck on your project..

 

Yah, thats why you see sooooooo many 13 second TBI thirdgens, right? Sorry to be a player hater... haha

 

yo Kevin Its all about knowledge and for you to respend lie that then you obviosly you dont have much eiher, not trying to be rude , but your a moderator so be nice, and bring you tpi on Im ready . any way my name is avi , and by the way I aso have a supercharged 383 formula ,1988. so my good friend put up or shut up, race me ad see what TBI can do... takecare and peace to yah....

 

by the way I just noticed your in cal. so whos paying for the tickets. for the big race LOL LOL ,anyway take care yu never know who you might se on the road SEEYAH

 

Let me get in here for a minute. I love this subject! I am right in the middle of changing my 350 TBI to a 350 TPI. It started as a '92 RS with a stock 305 TBI last July. I yanked the engine and installed a new 350 with a Holley Projection intake & 670TBI. The other mods are in my sig. I've also had major experience with my last car, another '92 RS with a highly modified 305 TBI 5-speed. Everything but the short block was modified. It ran very low 14's (kept up with & launched harder than my friend's stock '92 350/Z28/A4) and really ran strong up to 6,000rpm, but it was also very quirky. The high idle at startup, running rich no matter what I did, and other annoying TBI quirks.

After all of my recent TPI research and previous experience with TBI, bottom line is, I want TPI for it's smooth idle, monster torque, awesome looks, and whatever else is cool about it! Can anyone argue any of those points? Aside from the cost to swap ($2,000+ to do it right), TPI is by far the best way to go on an f-body. Don't get me wrong, my last RS hauled *** , but TPI is much more refined.

FYI, I'm adding the following parts to the engine in my sig:

Edelbrock Hi-Flo TPI base & runners, port matched of course. Ported stock plenum, 52mm TB, the new Accel injectors, new GM '92TPI harness, and uh.....oh yeah, ACCEL DFI! I have no love loss what so ever with my 8 years with TBI.

------------------
'92 RS, ZZ4 10:1 350, Edelbrock 6085 heads, Crane 208/214 467/482 cam, GM/LT4 1.6 true roller rockers, Holley Projection TBI intake, Holley 670 TBI, SLP/Jet-Hot 1-5/8" headers, Catco 3" cat, Flowmaster 3" catback, Hughes 2500 stall converter, stock 700R4, Auburn Pro posi w/3.42, 17x9" SS rims w/BFG tires, Medium Quasar Blue w/white SS stripes, 48,000 miles....soon to be an Accel-DFI Speed Density TPI!!

 

maybe i need to explain what losing low end torque means to me. our cars make about 220lbs from 2000rpm through about 2800rpm, with a peak of over 250hp, that is a lot of low end kick. the 305tpi makes 300lbs of torque@ around 32-3300 rpm, and thats it. batch fire port injection motors tend to have very peaky power tables and they usually don't start making power until further up the power band. from the time my car was unmodified i could launch and get through first gear ahead of my friends 91formula350, and it's all because of where the power is and how long it carries. tbi produces nothing but torque, and it does it from idle.

lata
tim

------------------
91 Camaro RS-LO3,Auto.
14.301 @ 94.39mph
The car is going street strip for next season. 13's here i come!!!!!
Edlebrock TES Headers, Cat Eliminator Pipe, Borla Adjustable Cat Back,Marche Pulleys, HyperTech Chip,Transgo Shift Kit,B&M Convertor(2000stall),Steve Spohn Rear Rig( all rod ends), Poly Front Bushings,Ported TB, 350 Injectors, Edlebrock Performer TBI Intake, Performer Heads, 1.6 Roller Tipped Rockers
http://www.mycar.net/mafb/registry/detail.cfm?id=299

 

If TBI is so much better than TPI then why doesn't GM put it on the LS1's and the new LS6? just curious, thanks.

[This message has been edited by 91Bird305 (edited January 12, 2001).]

 

Were talking about long versus short runner intakes more than TPI versus TBI. A well matched long runner intake will outperform a short runner intake in the lower rpm ranges. The short runner intake will out perform the long runner in the upper rpm ranges. This starts happening somewhere in the 4000-5500 rpm ranges. These long runner intakes are designed to increase the air / fuel charge that makes it to the cylinders in the lower rpm ranges but this same feature becomes a restriction in the upper ranges.

I am also a big proponent of talking torque not horse power because I like to talk apples to apples. Long runner = more torque down low, short runner = more torque up top.

With that said a short runner EFI can make completely acceptable torque down low compared to non EFI. This is because of its superior ability to meter fuel. With EFI, you can build great low end torque with a short runner intake and great race winning top end torque.

For the guy with the zz4 and Edelbrock heads... you have a calibration issue if your car will not idle properly. check my sig for my combo... idles very nicely and makes 10" of manifold vacuum at my 6000 ft altitude.


------------------
1988 T/A,
9" Ford, 3.50 gears, Auburn posi, 700r4 -w- 2100 converter
350 .060 over with forged 1 pc rms crank, and forged TRW pistons, 9.5:1 cr
Factory GM heads Pocket ported, 2.02/1.60 valves, back cut
Comp Cams roller 219/227, .479/.480, 112 LSA
Holley 700cfm 4bbl on TBI truck 7747 computer and chip by Howell-EFI
Edelbrock Performer EGR intake, Edelbrock TES and 3" cat

 

And your best time is what? Mine is low 13's with my previous engine, and my new engine will run mid 12's. What does your 383 TBI run without the blower? Did you try that? Did you ever get your car dynoed? I have 285 HP and 380 TQ at the rear wheels with my previous engine, how about you?

[This message has been edited by Kevin91Z (edited January 12, 2001).]

 

91bird305, my point is just the torque band that tbi is capable of producing. the reason gm moved toward port injection and more specifically, sequencial injection, is because it is more efficient to make equal amounts of power. also, from a marketing point of view it is easier to sell a big hp number to a semi informed comsumer than a big torque number. i am not trying to cut on any of the other forms of injection, i just like the fact that i can out 60'(1.9's) many of the guys who have port type injection set ups, even many of the lt1 guys, and it's all because of a good torque table.
gm knew that tbi was capable of building huge torque, the proof of that is the fact that they used it in trucks all the way up to 1995, long after every other vehicle in the gm line up was port injected, and are still producing it for towing applications in africa and asia(they use it there because wet flow manifolds are more thermally efficiant than dry flow)
my view of drag racing and really any form of racing, is that it is all about getting things moving. whether that means a good 60' time or getting up the hill out of turn 5 at road america, you need a good, flat, and long torque band to out do the competition.

lata
tim

------------------
91 Camaro RS-LO3,Auto.
14.301 @ 94.39mph
The car is going street strip for next season. 13's here i come!!!!!
Edlebrock TES Headers, Cat Eliminator Pipe, Borla Adjustable Cat Back,Marche Pulleys, HyperTech Chip,Transgo Shift Kit,B&M Convertor(2000stall),Steve Spohn Rear Rig( all rod ends), Poly Front Bushings,Ported TB, 350 Injectors, Edlebrock Performer TBI Intake, Performer Heads, 1.6 Roller Tipped Rockers
http://www.mycar.net/mafb/registry/detail.cfm?id=299

 

Also, look at TC's 350 TBI in his RS. He did every TBI trick in the book, and had nice heads, a nice cam, etc. It made 230 HP and 330 TQ at the rear wheels. Almost exactly what my 350 TPI made with a small cam, stock iron heads, and a stock unported TPI intake. Then I added the ZZ4 cam, aluminum heads, and ported my stock intake, to make the HP and TQ figures I quoted above. So where is the TBI advantage? Sorry guys, I'm really gonna get the heat on me now, hehe.

 

yo kevin, you misunderstood me . I ment the camaro 350 tbi convertible thats the car PABLO talks about in THE ULTIMATE TBI . the formula you cant handle so dont even bother..
not to be rude of course. :P and for the money , TBI rules period..

 

They say one picture is worth a thousand words. I switched: http://24.1.139.249/images/122000/DCP_0109.JPG

And it was well worth it in all regards.

------------------
Chronologically challenged. But still kicking!
92 CAMARO RS
305 TBI 5/spd (now TPI)

'69 camaro-BB/Lenco,1050 dominators, /Pump Gas/no drugs 8.97-150+

[This message has been edited by Dyno Don (edited January 13, 2001).]

 

my bad.... its ( SUPER STRONG TBI COMBO) AND about TCs TBI 350 , well he just needs a lot of tuning or something.. but this is about helping a fello thirdgen'r so I still stand by what I say for the money, TBI rules

 

I am not trying to start a war here and this is a legitamate question, but if TBI is better than TPI how come no one swaps out their TPI for a TBI system?
AGAIN THIS IS NOT A FLAME.
From what I am getting out of this, is that TBI makes more torque. And from what have have always been told is that torque wins races. One more question. If you matched up two equal engines, put TPI on one and TBI on the other, which one would win in the quarter mile?

 

For your 1/4 mile simulation, it depends on how the motor is built. If you are building a low rpm motor, the TPI will most likely win. If you are building a motor that revs to 6000+ the TBI will have the advantage of over the stock runner length TPI... now run a short runner intake on the TPI and its likely to be a wash. Either system if used in an intelligent manner will bring great results.

Why dont more people run TBI or convert from TPI to TBI? Well I'd say its because the TPI cars start with a much stronger package... better heads, better cam, more displacement, more fuel flow potential, and a better intake. So in stock form or with mild mods, there is no question that TPI is better than TBI... But once you get to the point where you have modified the engine that needs an intake swap the advantage goes to the throttle body because of cost. All else being equal, both motors with heavy mods (heads, intake, cam, throttle body, injectors) have the potential to make very similar power.

The TBI guys that arent swapping to multi point are doing so because they see that they can make the same power and spend less doing so.

Oh, most drag race motors are set up to rev high... this means that they are producing torque in the higher rpm bands which is saying they are making more horse power. Take two cars with the same sized motor... maximize one to make the best low end stump pulling torque you can and the other to make its power in the 5-8000 rpm range, the guy making power up top will spank the low end torque guy every time... easily

TPI can make more low end power than TBI due to its long runners. TBI can make plenty of low end torque but the nod goes to TPI. TBI can make high end power easily and cheaply... its costs more to build a TPI motor to make that race winning power up top.

------------------
1988 T/A,
9" Ford, 3.50 gears, Auburn posi, 700r4 -w- 2100 converter
350 .060 over with forged 1 pc rms crank, and forged TRW pistons, 9.5:1 cr
Factory GM heads Pocket ported, 2.02/1.60 valves, back cut
Comp Cams roller 219/227, .479/.480, 112 LSA
Holley 700cfm 4bbl on TBI truck 7747 computer and chip by Howell-EFI
Edelbrock Performer EGR intake, Edelbrock TES and 3" cat

 

Yes, one picture is worth 1000 words:
http://www.fbody.com/members/workman/TopTBI.jpg

------------------
1988 T/A,
9" Ford, 3.50 gears, Auburn posi, 700r4 -w- 2100 converter
350 .060 over with forged 1 pc rms crank, and forged TRW pistons, 9.5:1 cr
Factory GM heads Pocket ported, 2.02/1.60 valves, back cut
Comp Cams roller 219/227, .479/.480, 112 LSA
Holley 700cfm 4bbl on TBI truck 7747 computer and chip by Howell-EFI
Edelbrock Performer EGR intake, Edelbrock TES and 3" cat

 

to DAN W> you took the words right out of my mouth finally someone that knows something seeyah

 

Dan,
Thats the type of reply I was looking for. Thanks for not taking that as a flame. Most immature people around here get defensive when this topic comes up.
Myself, I am switching to TPI, only so I can get my car ready to eventually switch to a miniram. And because I bought a donor car with TPI for $400. But, unfortunately my swap wont be until summer. Thanks for the reply.

 

I am curious why people are talking about how a modified TBI is so much better than TPI. What if that person was to modify their TPI? Wouldn't it be better than the modified TBI then?

[This message has been edited by 91Bird305 (edited January 13, 2001).]

 

Because they get defensive when people say that TPI is better and they rightly feel the need to express that TBI is not a bad system. My opinion is that neiter is better... each has advantages and disadvantages. The biggest advantage I can think of for TBI over TPI is cost.


They could make just as much power as a person who modified a TBI system... and it would cost at least $1500 more. You could more easily run a centrifugal supercharger setup with this multi point system. The TBI answer to the power adder is you can easily run a NOS setup a-la carb style plate system. I think TPI's major advantage is the ease with which it can run a turbo or centrifugal.

Nope. The difference once the two are both modified is in the way they meter fuel. Both types of systems are proven performers... make no mistake, both can make huge power on a well designed combo.

------------------
1988 T/A,
9" Ford, 3.50 gears, Auburn posi, 700r4 -w- 2100 converter
350 .060 over with forged 1 pc rms crank, and forged TRW pistons, 9.5:1 cr
Factory GM heads Pocket ported, 2.02/1.60 valves, back cut
Lunati roller 219/227, .479/.480, 112 LSA
Holley 700cfm 4bbl on TBI truck 7747 computer and chip by Howell-EFI
Edelbrock Performer EGR intake, Edelbrock TES and 3" cat

 

So, badbrd383, what are your power and torque numbers? Without the blower if you can? My car doesnt have a blower so you cant compare numbers like that. Car Craft had a build up of a 383 TPI with a SuperRam and a blower on it. It made 500 HP and 600 TQ at the rear wheels. Is your car at that level?

My dad (Dyno Don) switched from TBI to TPI, and he says he has more torque, more power, and better drivability. We will be getting it dynoed soon to see the difference. With the TBI system on it, it made 158 HP and 220 TQ at the rear wheels.
TPI makes more torque than TBI. Thats a fact. Its the way the intake was designed. TPI is known as being a torque-monster. All I'm saying is, if TBI was such a hot setup, more people would be running it. Instead, you see a lot more and a lot faster cars with TPI or other multipoint injection systems.

Dan W, whats your power level with that aftermarket TBI system? Did you have it dynoed?

 

gee price difference: converting to Super Ram and all the needed upgrades to TPI injectors, TB, and stuff vs. Edelbrock RPM carb intake with TBI adapter. hmmm...

BadBird doesn't have a blower. he has a Vortec 350, Edelbrock RPM intake and 454 TBI.

------------------
-Tas
'89 Formula WS-6
[soon to be Torch Red with black hood and headlights =) ]

305, TBI, auto, 14x3 chrome flat based open element with K&N, functional Formula hood, cross-flow Flowmaster, '99z28 rear pipes and tips....

Super GRK_Taz World
EFI & Intake Options
AOL IM: superGRtaz
ICQ 82881207

 

hello to everyone I just want to say that I like both TPI and TBI, because I have two cars, one with each.. The bottom line here is to help the person asking the questions. And I see that most everyone knows what thay are saying and have deep opinions. thats great.. Im new at typing my opinions and knowledge so if I come out the wrong way then . sorry. but I also have an opinion. and I think I know alittle bit too. Also, every car Ive tuned has gone realy fast, so I just want you all to know Im not talking out of my a-s.. take care to you all..........

 

I wish I could give you an exact number but I havent had it on the dyno yet.

The best I can do is give you my 1/8 mile mph. I've only got it to the track once so far and I had a drivetrain vibration that was setting the knock sensor off just before the 1/8 mile so the car basicly shut down after that... should be all straitened out now though. Anyway, the MPH in the 1/8th was 79... so if we go bench racing... in a 3400 lb car, that should be roughly 250 hp at the wheels. About what I would expect considering the altitude and those crap heads I'm running.


If you want to correct those numbers for crank and altitude, (20% drive train and 15% altitude) it comes out to about 345 horse. For whatever its worth I would expect it to run low 14's up here and low 13's at a normal altitude... however it remains to be seen.

That holley 4bbl has 65# injectors so it can handle a max of around 500 hp... and beleive me, there is plenty of room left in the calibration for more fuel... this tbi unit is overkill for the motor considering the stock heads.

Estimates are really the best I can give at this point so take them with a grain of salt... Maybe in a few months when the track opens again, I'll be able to give some better data.

 

Speed costs money, how fast do you want to go? I'm not happy with 14 second timeslips without a power adder, so I'm using TPI. Same with my dad, he switched to TPI.

And, He said he had a supercharged 383 in this thread. Thats not a blower?

 

ya guess I missed the post telling about his 383 Firebird. I've been following what Pablo has told me which concerns his 350 Camaro convertable.
with: Vortec 350, edelbrock RPM intake, and a 454 TBI.

 

I'm not either. You mod ur engine all out to run with stock Z28's? No fun. I want some low 13's or low 12's times. Now thats fun!

 

I'm not done with mine yet. That was the previous engine that ran those times. My new engine should run mid 12's. And its TPI. My dad just wants to run high 13's, he's happy with that. I dont want to run 11's because I'm not putting a roll bar in my car.

 

Kevin, Your dads goals should be fairly easy to accomplish.
Specificly, what kind of mods are you going to do to reach your mid 12 second goal? Is your car already a TPI car?

 

All 90-92 Z28's are TPI. Check the link in my sig above to my mods page, and then look at my future mods. I'm adding an LT4 HOT cam over the ZZ4 cam, porting my ZZ4 heads some more, adding a TPIS intake and runners over my stock ported intake, and going from SLP 1 5/8" headers to SLP 1 3/4" headers.

My dad's engine in my car now has run a best of 14.2 @ 98, and that is with me missing third gear twice. It should hit 13's as it is with the LT1 cam, but I want the ZZ4 cam in it anyway.

 

Ive seen a 305TBI with 150hp NOS on it run 14.3.
No other mods.

my 89 Formula 350 runs 14.57 STOCK. 350TPI.
no mods.