So my brother got a new thirdgen last week. it is a 89 350 t-top IROC fully loaded with a curb weight of 4150(that is what the door says). My 92 1LE 305 weighs in at around 3100 even. We both have a lot of the same mods but I have also ported my plenum and base and had my heads redone. You would think I would have him beat right? Well i finally catch him around 60 and just start to pull past him then. How can a 350 with less mods pull as hard as a 305 with over 1000lbs less weight. Not only that he has 2.7s and i have 3.4s! Please tell me it is becuase my SD computer needs some programming where as his MAF is less fickle. Anyway what is the weight to power trade off roughly when we are talking about our cars?

[This message has been edited by UVA3rdGen (edited August 20, 2001).]

 

That 4150 is the MAX weight, not the CURB weight. No way his car weighs that much, its probably more like 3400. Hes probably got you beat in torque, 350s are heavy in it with tpi, but your car is still faster. If you really want to beat him, invest in a new cam.

[This message has been edited by rezinn (edited August 20, 2001).]

 

What can I say....305s suck. It's not just the extra 45 cubic inches..it's where they come in that totally changes the dynamics of the motor. That being all in the bore rather than stroke.

The 305 is a long stroke, small bore engine. While that makes it feel reasonably peppy at very low rpms, it seriously handicaps it from making any real power. Exactly why that is takes a bit more explaining than I'm ready to do at 4 in the morning.

The 350 has the same stroke, but a roughly 1/4" larger bore. It may not sound liek much, or look like much in theory, but in reality that makes it a vastly more workable and responsive engine.


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"American made baby. 100% American iron. The muscle among the masses. My hero. Yep, you can take your ergonomically designed, space age, computer controlled, 4 door, cup holding map lighted split double wishbone split fold down retractable cargo covered moon roof piece of transportation and keep it. For I have felt the thunder. And I know the difference!"
JSP Motorsports
ICON Motorsports

 

Torque is king...

Thats why most people don't build up 305's. When it comes down to the internals, you can do many of the same things between 305's and 350's. You can even get HP's up there on both engines, but torque is much harder to get with a 305.

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1992 Pontiac Firebird 350/Six Speed
1987 Toyota Pickup 383/500+ HP

 

The weight of 4100 lbs. is with the car full of passengers and full tank of gas, at least that is what I was told.

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'86 IROC
T-TOPS, TINTED WINDOWS, BRAKE LIGHT BLACKOUTS
GM GOODWRENCH 350
EDELBROCK TES HEADERS
FLOWMASTER, NO CAT
EDELBROCK 600CFM CARB.
KN AIRFILTER
ACCEL HEI DISTRIBUTOR
160* Stat
2:73 GEARS
Rebuilt 700R4, with manual valve body
B&M Megashifter, 5" Autometer Tach w/shift lite
Soon to be installed
3:73 Richmond Gears and 3" Hooker Aero Chamber
Corvette Servo & .500 boost valve
15.61@ 95.2mph G-Teched, 1-2 shift slippage, and just replaced a burnt plug wire
"There is nothing more addicting than speed"

 

This is going to disapoint everyone, but almost all new engines are square(bore=stroke) for emissions and fuel economy reasons. The day of the short stroke big bore engine is slipping away. Thankfully the marvels of modern electronic fuel and spark management can make up for a lot of that. Square engines also tend to run pretty well under pressure since you have an easier time filling that long skinny cylinder. That means that blown or turbo late model square bore engines can still kick a$$ and get 30 mpg.

 

I thought that sounded way way to heigh. I guess if you want to add it up the main wieght differnce is he has A/C, Bose system, rear seats, front power seats(mine are sparcos), smog pump and system, rear truck lid, power everything, factory radiator(I have alumin griffin) and a automatic tranny. Even with all that wieght saving he gives me a damn good run for my money and with a couple more mods with probibly beat me . We were swaping parts around yesterday and I gave him my gutted air box and he had less low end and I had less high end on his factory one. I had no idea that air box would make such a differance. To end this discussion do you think a 350 will always gain more power from bolt on mods then a 305 so that with ever mod he will get harder to catch, even if I do the same thing.

 

What are some square engines, I think i remeber some guy a while back taking about a 337 or something crazy like that. Wouldn't you have to clearance the block a crap load to fit a 400 crank into a 305.

 

"do you think a 350 will always gain more power from bolt on mods then a 305 so that with ever mod he will get harder to catch, even if I do the same thing."

Yes. More ci., more power.

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89 RS

STILL Looking For:
An 87 IROC-Z28 350 TPI


[This message has been edited by IROCZTWENTYGR8 (edited August 20, 2001).]

 

A square engine is one where the bore = stroke.

You must be talking about a 334. 305 block, 400 crank (3.75" stroke). Total waste of money and a good crank, IMO. To go to that kind of expense on a 305 block is just stupid.

 

Square engines that I am certain of.

4.6 Ford
5.4 Ford(undersquare)
Jaguar/Thunderbird 4.0
Ford Powerstroke
BMW 740d
4.6 Northstar
3.5 V6 based off Northstar
The LS1 is close, but bore is still bigger than stroke.

Those are the only one's I'm absolutely sure about, but I think that there are a lot more.

[This message has been edited by ATOMonkey (edited August 24, 2001).]

 

OK, my knowledge of 3rdgen trivia is amazingly poor, but weren't all T-top cars actually 305s?



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1984 z28 w/ a 357 cu in. monster engine which is looking like the posterchild for Edelbrock with the exception of the Holley 750vac... all the suspension stuff... 9-bolt posi disk is in...

-=ICON Motorsports=-

 

T-Tops and 350's were good to 89 then GM thought that tp many of us would twist are cars into pretzels and only the formula (odd reasoning) got t-tops and 350's 90-92. Oh well. I got an 89 with T's and love it.


Oh and yes every build up I have seen is that bolt on for bolt on 350 will make more. CI is king. But a well done 305 can be good as it will make other big cubes jealous. but dollar for dollar 350 or large will always benefit more from bolt ons.

Ok Ill stop now

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1989 Trans Am GTA, 5.7L TPI, TH700-R4, T-Tops, dual cats, 9-bolt rear, 3.27, Dynomax muffler, K&N
1992 Camaro RS, 5.0L TBI, T-5, T-Tops, 3.08, L69 Dual Snorkel, K&N - Sold

 

ya, well in some ways I do not blame GM for stoping 350 + T-tops, this car has headers, exhuast, custom built B&M tranny, and lots of little mods and when you mash it you can hear the t-tops flex over the roar of the engine. Even with out the 350 when going up my driveway the entire thing flexes like crazy. My car (92 1LE) I bought with a roll cage so I never knew these cars flexed so much.

 

If your car flexes that much u should get SFC's. IMO, every T-Top car that that is making power, (350 TPI or 305 5 Speed G92) or is going to be bulit up and modded for power, should have SFC's.

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89 RS

STILL Looking For:
An 87 IROC-Z28 350 TPI


[This message has been edited by IROCZTWENTYGR8 (edited August 24, 2001).]

 

I'm kinda surprised that no one has mentioned that in stock config a 87 350 and a 91 1LE 305 ran about the same times. If your car is falling that much behind the 87 and your car has more mods, I'd say your car is out of tune or the mods are mismatched.

 

Mine's a T-top.

Of course I have SFC and a 6 point bar in the car and I've never twisted the car enough to have a t-top fall out.

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Follow my racing progress on Stephen's racing page
and check out the race car

87 IROC-Z SuperPro ET Bracket Race Car
461 naturally aspirated Big Block

Best ET on a time slip: 11.242 altitude corrected to 10.89
Best MPH on a time slip: 121.52 altitude corrected to 125.89
Altitude corrected rear wheel HP: 497.9
Best 60 foot: 1.546

Racing at 3500 feet elevation but most race days it's over 5000 feet density altitude!
Member of the Calgary Drag Racing Association

87 IROC bracket car, 91 454SS daily driver, 95 Homebuilt Harley

 

I have the SFC in my garage, I am going to have somebody weld them once I see if they clear the exhuast on the passenger side. Do the subframe connectors actually have to connect to anything in the back because mine connect to the front tranny cross member but end short of the rear subframes. Quick question off the subject, how much power can I put into the 9bolt in the IROC before I have to start worring about breaking stuff?