I have an LO3 with edelbrock headers, torquer heads, 1.6 RR. With a conversion to Speed Density TPI and a roller cam like a 208/214 comucam would I be able to come close to 300HP? The engine would be rebuilt for reliability to make sure I don't have to tear the engine down 6months after the swap.

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305TBI FireBird, Holley Intake and TBI, Headers, Torquer Heads, Gears. Best E.T. 15.08 at 92.5, 0-60 6.45.(Before Heads)Summit cam purchased 204-214, to be installed "soon". And maybe a TPI swap,

 

I'd say you'd be looking at 225-260hp depending on what you do to the TPI. Stock TPI would give you the 225, where a modified TPI would give you close to 260. Modified would mean an aftermarket base, larger runners, ported plenum, and 52mm TB. The size of the fuel injectors would also come into play. I would recommend 22lb/hr for your modded 305.

FYI: I'm doing a very similar conversion, but with a 350. I was going to use TBI, but I've been doing a ton of research on TPI. My only initial hesitation with TPI was the cost, but I think it's worth it overall and in the long run! Plus it looks sooo coool!

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'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....

 

I think 300hp is accurate for that combo. The only thing is to make the TPI flow a little better. At a minimum, port the upper and lower base or get an edelbrock base, and if you can, get some good runners. The cam seems pretty good for TPI, I wouldn't go any bigger. If you want an easier route, you could go with a Holley 670cfm throttle body and either port your intake, or get an edelbrock one and use a high flow air filter setup(dual snorkel, or open element). Then you would need a custom chip, which you would need with the TPI anyway. I thnink the HP should be comparable for a lot less money and headaches. Just food for thought.

89 Transam GTA, a few bolt ons

 

My friend put TPI and an SLP cam in his LO3 with only cat and cat-back mods, and it gave him close to 1 second on the 1/4 mile.

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1987 Chevy Camaro IROC-Z
L98 TPI 350 (5.7L)
TH 700R-4 Transmission with 2.77:1 Rear End

Current Mods: Edelbrock TES 1 5/8" Headers, Hooker 3" Aerochamber Cat-Back System, Performance Resource Chip with 160* Thermostat, Accel Ignition Coil, Cap, Rotor, 8.8mm Wires, K&N Filters, JET TPI Air Foil, All Free Mods, Falken ZIEX Z-Rated Tires.

Best ET : 14.32 @ 97.7mph
(corrected for elevation)

Next on the list: LT4 HOT Cam

 

Modifications on the Tpi will cost you lots of money and will gain you lots of HP but you can gain HP in other ways as well! I currently have a 305 TPI and I have been looking to gain a little HP myself! Start off with a $50 airfoil from Jet or TPIS! If you're unaware of what an airfoil is, it goes in the middle of the throttle body to smooth airflow going into it! This little baby will gain you approx. 12HP and 40-50 CFM increase!! Also you might try an Adjustable Fuel Pressure regulator and increase your fuel pressure about 5 psi...this will definitely increase the HP! If you're going to use a Speed Density TPI then you can also get the K&N cone air filter that fits right onto the throttle body! This will most definitely give you a HP increase! These mods alone will put you close to 250HP and you won't have spent a lot of money! Now if you modify the TPI completely (bigger throttle body, runners, intake base, ported plenum) AND do all my other suggested mods then you will most like be around 300HP and probably a little more! Be careful with the cam on TPI tho'!! I recently decided I wanted to change mine and started doing research and found out that you MUST use a cam with a 112 or 114 degree lobe seperation angle due to the runners on TPI! Comp cams makes specially designed cam for TPI in all applications! I suggest ONLY using these cams or your performance will go to S**T!! I hope I could help you!

 

There are lots of company's that make cams specficlly for TPI engines. TPIS, LPE, SLP and GMPP all make cams for TPI and LT1 motors.

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1987 Chevy Camaro IROC-Z
L98 TPI 350 (5.7L)
TH 700R-4 Transmission with 2.77:1 Rear End

Current Mods: Edelbrock TES 1 5/8" Headers, Hooker 3" Aerochamber Cat-Back System, Performance Resource Chip with 160* Thermostat, Accel Ignition Coil, Cap, Rotor, 8.8mm Wires, K&N Filters, JET TPI Air Foil, All Free Mods, Falken ZIEX Z-Rated Tires.

Best ET : 14.32 @ 97.7mph
(corrected for elevation)

Next on the list: LT4 HOT Cam

 

I wasn't tryin to imply that Comp Cams was the only company to make TPI cams! But I know that if you'll check you will see that Comp Cams makes the most "affordable", quality cams! The others are great cams but a little more expensive! It's up to you but I've always had the best luck with a Comp Cam!

 

I do have a 670cfm Holley on a projection intake manifold with a custom ed Wright chip but after my headswap the car never ran correctly after trying for months to tune it. The acceleration feels about a half second slower and I get aroun 11-14mpg depending if it feels like running correctly or not.

 

Sounds like if the headswap was your problem then you should try a different set of heads or go back to the ones that were working right to begin with!

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1986 Trans AM
305 TPI
Completely Stock
Soon to upgrade to a 327 TPI with pocket ported 64CC heads, comp cam, TPI air foil, Adjustable Fuel Pressure Regulator, possibly bigger injectors!
Current project: Installing an Accel Inline Fuel Pump since I've been through 3 Fuel Pumps in 2 Years! :-(

 

The stock heads sucks *** . The ones I have are stock replacement 305 Torquers.

 

300 HP at the crank, or 300 HP at the rear wheels. My L98 doesnt even have 300 HP at the rear wheels, yet...


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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=-

 

Crank, I know that with an auto it would take about 350HP to make 300RWHP. Although that would be cool, too .

 

Mike,

I was quoting rear wheel numbers too. Don't forget that you still have a stock LO3 short block, which only has about 8.5:1 compression.

Those 305 Torquers should work fine. I did have the same "tuning" problems as you did when I had ported L98 heads, Crane TBI cam, carb intake, 670TBI, headers, custom chip, etc...on my last '92 RS. I never did get it tuned just right. It always ran rich. I remember when I sold the car I changed most everything back to stock except for the cam & exhaust and it ran better! Perhaps not the same power, but much smoother and more responsive. I wasted alot of money on that setup!

Yet another reason to switch to TPI.

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'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!!

 

How long did your TPI swap take? I have changed the fuel pump before and it is a PITA. I dropped the exhaust and actually had to cut a section that goes over the axle to be able to get the tank down. Also is the wiring harness more complicated than the fuel pump? And the lines I gues are pretty straight forward. And do you think it was worth it? I plan on keeping the 305 and rebuilding it. I just have a thing for wanting a 13 second 305 car . There are many who believe it can't be done near where I live. Also it'll get about 1-1.5mpg better, every little bit helps. Thanks

 

You cant expect to tune your car unless you are doing the chips for it, anything else is just wasting your time. There is far far more in that combo than you think there is (with TBI). The fact that your fuel mileage is crap tells me the bpw is probably wrong, Id bet one of the reasons its so slow is because WOT is rich too, the injectors the holley comes with are huge (and crappy)

May I suggest putting your old injector pod on there, and running the stock chip? I think youll be pleasantly surprised

I run the stock injector pod and stock injectors on my holley 2" TB (at 19 psi, but the chip is calibrated for it) and Im quite happy (I have a complete tpi setup in my garage and havent swapped if thats an indication)

[This message has been edited by Pablo (edited December 24, 2000).]

 

Pablo,

Want to sell that TPI setup? I need a plenum and a complete fuel rail assembly for my speed density conversion.

 

Hey Scott C. Right on, I'm right in the middle of doing the same swap! I considered the big cost of it too, but I agree that the looks of it alone, let alone the improvement in performance makes it worth it! I've got all the TPI parts stacked in my garage, and a L98 at the machine shop!



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89RS w/350 TPI; 69RS/SS w/450 HP 350/Muncie 4-Speed "Too weird to live, too rare to die."

 

Very cool Pat! What parts are you using for the TPI? Stock or aftermarket? I just ordered $1,000 worth of TPI parts yesterday! Woohoo!

Good luck!

 

Well, so far I got a TPIS AFPR and airfoil for it, other than that, the rest of it is still stock right now. You ought to see the pile of parts! I got the dual fan setup, all the air intake parts, including the MAF, an entire engine harness with ECM, and a whole gas tank with the right fuel pump in it. It's been a real wild goose chase rounding up all the parts, but besides spending too much money, I've had a blast doing it! My RS is trying really hard to resemble an IROC. Lol. The other things I've already added to it are power windows, power mirrors, overhead console, rearview mirror w/maplights, 145 mph speedo and 5,500 redline tach, aluminum driveshaft, IROC swaybars and wonderbar, 3.42 aluminum drum rearend, 91-92 Z/28 hood, IROC driving lights and grill, and polyurethane tranny and torque arm mounts. Damn, my list just keeps getting longer and longer, and it will continue to grow with every paycheck! (Grin) P.S. Modifying your car is like a bad drug addiction, once you start, it's damn hard to stop!

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89RS w/350 TPI; 69RS/SS w/450 HP 350/Muncie 4-Speed "Too weird to live, too rare to die."

[This message has been edited by Pat Hall (edited December 29, 2000).]

 

Hey Guys:
Check this one out I just finished it last week, it runs great, now to just change the peanut cam. http://24.1.139.249/images/122000/DCP_0108.JPG

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Chronologically challenged. But still alive!
92 CAMARO RS
305 TBI 5/spd (now TPI)
'69 camaro
BB/Lenco
1050 dominators
8.97-150+
Pump gas/no drugs

 

Very nice! How does it run? What size cam do you expect to replace the peanut cam with?

Looks like many of us RS owners have our own secret TPI projects going on! Keep it up!

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'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!!