Inliners International Forums General Discussion Engines Engine Mods to achieve HP

Has anyone seen engine modifications organized to achieve certain HP and Torque levels. For example, a list of modifications (upgraded exhaust, ignition, headers, etc.) and the general HP and Torque improvements that could be expected. I want to get about 250-275 HP from my in-line 250. What kind of mods are most cost effective to make to achieve that?

The most productive modifications are to the way the engine breathes. A good intake and exhaust system that works within the rpm and load range the engine will be operating at. A good ignition system that will help the fuel and air mix burn correctly and completely will insure you get all the engine is capable of giving. Increased compression is a time tested way to get more horsepower.

The horsepower range you are looking for is a reasonable goal for a street driven 250 if you select all the components carefully so they all work together. Santucci's book is well worth the cost when planning a 250 family engine. It covers everything from mild street engines to all out drag engines. It can be bought right here from Club Stuff.

Mike, in your response to Witherer, you reference the 250 family engine. What is that and what engines are included in it?

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inuke

Inuke, The 250 engine family was first produced 1963 starting with the 194/230/292. The 250 came out a few years later. They all share the same components, distributor, cam, etc, with the exception of crank, rods, and pistons for displacement. The 292 is an exception as well because the block is taller for the long stroke. They all share the same bolt pattern for the bell housing as a SBC. There are other things to watch for and I'm sure others will catch anything I missed.

Larry

Compression is always the best way to go for driveability. It may cost more for pistons but it's well worth it. Bigger or more carburation may bring higher HP at the top end but if you drive nomally on the street you want it to "go" when you push on the peddle with out dropping 2 or 3 gears. Giant valves are great for RPM but kill lowend torque. Same for a big carb. or big open plentum intake.

It all ties together when you get what you want. If it's all racing drivability suffers. An engine that runs between 1500 and 3000 rpm is best done with compression and an advanced cam. Not wild but mild. A properly curved distributer works wonders. All engines are just air pumps. They don't care what they are doing.

The weight of the car, how it's going to be used, and pleasing you as the owner/driver is the most important thing. Good Luck

a 468/505- 530/530 lift is a good range to look at for street use.These cam work good between idle & 5500 rpm and have a 112 lobe separation
which can give a smooth to a slight Lope at idle depending what you go for. The Offey is the Better daily driver Intake. Which Gives good lowend to Mid. range Power and torque. Topped with a small 4b and Dual exhaust.
As to the head you need to get it to Breath.Cleaning up the Ports Is a good place to start,and at the very least a good 3 angle valve job. Doing a lump port to the head Even with a stock size valve can Add a great deal of added CFM
Over stock (with the stock valve) Personaly a up grade to a larger valve 1.8 Is good for a daily driver If your still looking to keep some MPGs. But if your not worried about the MPGs then step it up to a 1.94 with a 1.6 on the exhaust. Even with a 1.8 intake It is better to step the exhaust up at the same time.And going to a bigger valve is not going to hurt your low end.One of the first up grades I made many years back to my 250 was a Nice Rv style cam Offey intake and Headers along with a Head with 1.8 intake and a 1.6 on the exhaust.I ran it for a few years with just the intake & headers. and that In it self was a surprize Over the stock set-up. Then a Much bigger difference when I installed the Cam and Head. After that all heck broke Loose. I was a Inliner for sure.Then I went and Built a Fresh Motor. But more on the wild side. No more RV cam
I went right to a solid lift 583/607 Jumped the compreeson to over 12-1. Now to me This was a Nice HOT Street hehe.
Mind you the Motor was Not very Happy with the
stock 3:08 rear end.

BUT anyway If you pick the right cam and a compression between 9/10-1 But with todays gas prices You may want to stick closer to the 9 9.5-1 compression a offey intake and dual exhaust small carb. You won't have much problem getting your 250HP. That is a Fair goal for a daily driver.BUT bottom Line is YOU have to get that
head to Breath.

Have you seen the article in the June 2005 Hot Rod Magazine, reporting on a series of dyno tests by Sissel on a 250 and a 292. It supports the above comments by Larry, et al.

IIRC,the Sissel 250 made 300HP with the 12 port street aluminum head,w/a mild cam & 10-1 compression?
MBHD

Here are some extracts from the Sissell article : Page 5, Page 6, with flow data, Page 7, with 250 and 292 HP and torque

I'm sorry but has anyone some bigger pictures of the article it is not really easy to read it

I'm really interested in the article, because i want to rebuild my own 292.

Thanx a lot!!

Photobucket seems to have decreased the resolution of my scanned images of the article. My originals are very good resolution, but when I downloaded one of the images from my post it was hard to read. When I enlarged it it all I saw was the individual pixcels. For those with no easy access to HRM (e.g., Inliners living in Brazil, the Netherlands, etc.) I could send the higher resolution images. Send me a pm with your email address. I feel kind of strange about doing this; should a dedicated 261 guy be enabling the building of late model engines? Why not, they are still Chevrolet sixes, are they not?

Good info. Has anyone adapted to throttle body fuel injection, or multi port injection? I suspect you'd get better MPG and throttle response. Any significant difference over a carb setup for street use?

Hoyt,

you've got a PM!!!!

HRM back issues are vailable, for $6.00 plus $3.00 S&H. Somewhat pricey.

i think for normal street use, the difference between injection and a carb would be minimal. atleast for a stock application. as the power goes up then fuel injection definately has it's advantages. tom