Adding Horsepower - how much does if effect transmission

[jer_bond]

1975 Cutlass Supreme Supreme S (automatic; 350 4bbl; 170hp but 275ft lbs of torque; rear-wheel drive; 4-door non-vinyl hardtop sedan; 100000miles; just over 160000km; built in Lansing Michigan)



The caltalytic converter on my '75 Cutlass was removed; wondering if anyone has a quess on how much horsepower is gained with this part removed from the exhaust system. Also, can anyone tell me how well my automatic transmission(rear wheel drive) would withstand addition horsepower from adding a performance exhaust? And would adding a slighly bigger-than-stock carb put too much pressure on the transmission. How much could I modify the engine in terms of adding horsepower before I would have to modify the transmission. All help is much apreciated. Thanks.

[xeroinfinity]

Without the CAT you might have gained 2-3 hp, but probly no gains , the OEM Cat is pretty high flowing.

Dual exhaust might possibly give you 8-15 HP.

Your Cutlass has either a 350 or 400 turbo trans, the 400 turbo is better for power adder, they can handle 250+HP & ft lbs of torqu ... easily.
Just dont do neutral drops!

If you were putting out 350+ hp then you could rebuild the trans with some performance clutches and a shift kit.
A shift kit can usualy be added with out removing the trans, just dropping the pan & valve body.

Hope that helps Good Luck

[maxwedge]

It has a 350 trans and the condition of the trans is more in question here than how much power it can stand, as xeroinfinty stated minor mods to the unit will beef it enough to handle any 350 without internal mods or nitrous. But this unit could be " tired" to begin with.

[xeroinfinity]

I know my 76' 442 Cutlass had a TH400, it was just a Old's350 CI also.
I didnt even consider his mileage... I know at 125k miles I destoried my trany... doing Neutral drops

Other then that they are good transmissions.

[jer_bond]

Thanks for the help guys. So now I know it's better to stick with mild mods and stay in and around 250hp to be safe. I'm going to add a better flowing exhaust sytem. I'm not sure whether or not upgrading the headers will make much of a difference 'cause I'm not sure how restrictive they are on the 1975 350 engines. I heard that the carbs are the most restrictive part in the intake/exhaust system for 1975 350's so is it necessary to get a better carb? I'm think maybe a 650cf and a new exhaust system will give me 80 more hp from the stock's 170hp to bring me up to 250hp. Or can anyone tell me if that combination would add too much; would that bring me above 250hp?

To make it simple; what mods should I do to bring me up to 250hp from 170hp?

p.s. I guess I won't be doing any more neutral drops; never really questioned how much damage it does.

[maxwedge]

80 hp, this would require a head and cam change! The entire engine is a low compression small port engine that will not see 80 more hp without major changes.

[xeroinfinity]

Yeah just because an ad says a set of heads or exhaust mod would give you X amount of HP gains, is usualy not true.
Without a Dyno test its hard to relay say what will give you how much in hp gains.

And as Max said, just a carb and exhaust mod you wont go put you over 250 hp.
I wish it was that easy.

ps- neutral drops tend to break the planetary gears into small pieces...
....leaving you walking to the trans shop.

[jer_bond]

Thanks a lot for the input. Looks like this restoration/project is gonna take a lot more time than i thought. I'm gonna have to do a lot more research now.