Inliners International Forums General Discussion Hi Performance 250 Power rating

Well I took the plunge and decided an inline for my Hot Rod was the way to go. Its back from the machine shop now so there is no turning back, but I wanted an educated guess on what you guys think horsepower would be.

Started with a 63 Chev 230 Block.
Isky 262 Supercam and spring set.
Mild Port and polished 230 head, decked .030
1.84 Intake, 1.60 Exhaust, 3 way performance valve job.
Bored .030 over with 307 Flat top Hypertech pistons
New Ballanced 250 Crank.
Offy dual carb intake, Dual 2bbl Weber/Carter Carbs.
HEI dizzy and coil from Tom Langdon.

So its really a 254 now I guess.
Thoughts on how many ponies?

Maybe 200. Are the bolt bosses still in the intake ports. Remove them and you get a bit more.

Do you mind saying what your cost was to build that?

Stock exh manifold? I agree with CNC , about 200 hp. Get better than stock exh and see around 210-220.

Sounds like a fun engine. Get some vid and pics.

No not a stock exhaust maniflod at all, I fabbed up a dual lakes style header, so plenty of flow there. As for cost I'm in Canada so basicly 30% more for parts because of shipping and brokerage but I'm into it for about $3000 so far including the machining bill, and cost of the block. The bolt bosses are still in, from other posts I read, including Leo Stantucci's book, for street rod its better to leave em in unless you are going to the lumps. I Shaped them like wings as best I could to improve flow but read that any increase in volume is lost by the decrease in air flow if you just take them out. Once I get it painted I'll post pics.

So 210-220 With the headers, thats not bad, the 4:11 gears will probably scare the average 350 for the first 3-4 blocks anyways

That is totally false! The lumps always increase air velocity into the port and redirect to flow correctly through the bowl area by creating a short side radius it doesn't have otherwise. We did a series of dyno tests on here on both the 292 and 250, and it was proven that your statement was another one of those "urban legends" that had absolutely no truth to it. A comparably prepped lump head always made more power and torque at the same RPM than a head with no lumps. Also, tapering the bolt bosses was shown to be of no benefit, your just simply not removing enough of it to matter, the remaining boss is still too much of a roadblock in the port. That was another myth that was shown to be just that.
Do you have any pics of your headers. What kind of car are you putting this into.

Was there dyno tests of a cyl head with the boss shaped like an airfoil & a cyl head w/the airfoil removed w/no lumps installed?

If so, what were the results?

What it sounds like is Leo's book is full of "urban legends" ?


MBHD

Yes, all 3 types of port configurations were tested. Stock intake port with no lumps, both with and without bosses tapered. Ports with the boss removed, but no lumps. And ports with lumps installed. All were also each tested with valve sizes of 1.72", 1.84" and 1.94".

Yeah, I see what your saying Hank about the comparison between a stock port with or without the bosses tapered vs. a port with the bosses removed with no lump installed. Yes, the port that still has the bolt bosses will provide better velocity than the one with them removed but no lump installed. For the street, yes that is a true statement, and like Leo also says, unless upgrading to a lump port, leaving the bolt bosses is better.
The OP seemed to be eluding to the fact that from what he had seen was leaving the bosses in place was better than installing lumps for the street. That is untrue and what I was meaning. Sorry for any confusion if thats how you took it.

If you wanna hump it, you gotta LUMP it! Check out youtube for some vids of lump installation. That was my only issue in the machine work (everybody around here at machine shops acted like it was chinese math) but youu can do it with a sawzall and a few drill bits. I'm gonna give her a try in the next few months.

66miles,
What's the 254 going into? Car/weight/trans/exhaust/4.11gears?
That way I can give U an estimate of what the car will do -

66,
This little $11 gadget will save you lots of time, impress the ladies, and make you look like a wizard at your next bench racing session:





Most of this info can also be obtained on line or through various apps but I like this slide rule because all the answers are in one place and you don't need a sixth grade education to make it work.

The car is a 31 Oldsmobile. So for weight I have an estimation of about 2200 lbs, Its really very light. The gear choice was driven primarily by what was in the Rear End I bought for it, plus looking at 29" Diameter rear tires. Its got a 4 link triangulated rear end and a 4 spd saginaw tranny. Build is still ongoing and stalled for the most part due to Summer. Can be found here though. I may have to ebay that calculator

http://www.jalopyjournal.com/forum/showthread.php?t=538052

In the end I figured if it came down to it and I NEEDED more, the lumps were still an option but 200+ ponies should be enough....well probably not and there is a chance I'll go all in anyways but I should drive it first and see.

Wow, if that 2200lb is right U will have all the power it can handle, tho from what I read the 31 Olds curb was 3000lb+/- so U musta taken some weight out!

DeuceCoupe Gonkulator says
Torq 253 at 3500
Powr 217 at 5000
That is about what the guys above already guessed, no big news there. I got 9.3cr but U should measure it.

Quarter Mile the Gonkulator predicts
2.09 60ft
9.07 at 76.5
14.30 at 92.4 (pushing some wind up there)
5.9 0-60mph
I bet that's quicker than your average 31 Olds.

DeuceCoupe,

Can you figure what my truck would run?

It weighs 3780 w/driver, & the 60ft time is 1.68
262 CI 6 cylinders.

Thanks

MBHD

Hank,
OK I will take the plunge and start a Gonkulator model for the 200/229/262 family, it is new to me, never had one. Any tips?

Also, as I gather the Syclone came with a 280 net hp turbo. Would U know the head flows on that by chance? And, what have U done to your Syclone past stock?

I guess it's somewhat relevant, in a way that 90deg v6 is just an SBC w/2cyls cut off, whereas our straight6 is also similar to the SBC but with a strange cylinder head etc. So if our L6 had the cylinder head etc of the 262v6 they might run as good as those.

[quote=DeuceCoupe OK I will take the plunge and start a Gonkulator model for the 200/229/262 family, it is new to me, never had one. Any tips?

Also, as I gather the Syclone came with a 280 net hp turbo. Would U know the head flows on that by chance? And, what have U done to your Syclone past stock?

I guess it's somewhat relevant, in a way that 90deg v6 is just an SBC w/2cyls cut off, whereas our straight6 is also similar to the SBC but with a strange cylinder head etc. So if our L6 had the cylinder head etc of the 262v6 they might run as good as those. [/quote]

The cyl head flow I believe is 165/119 in/ex @ .500 lift, awesome I will add & also this is with a 1.94" intake valve.

I run more boost than stock & I custom tune the factory ECU.

I would not say if the Chevy inline 6 had these heads they would make more power, the flow #'s are pretty weak.

I believe these are the worst flowing cyl heads Chevy ever produced for having a 1.94" intake valve in a V-8 & V-6 years made for full size V-8 trucks 1987-1992 ish?
Just look @ the TQ drop off so fast.


MBHD

Hank,
What trans and rear are in there? Stall spd? Guessing it hooks pretty good by the 60ft.

Found some stuff on the 200/229/262 yup the heads flow kinda sick, makes me feel better about the old straight 6. Turbo makes up for a lot.

Hank,
Thx 4 the prod I even learned some stuff building the 200/220/262 v6 Gonkulator model. Kinda snoozers as they came out in the 70'80s.
When I model these in the Gonkulator it spits out not only net hp (the factory ratings) but gross hp (the way the 60s cars were rated).
So here are some comparisons - the gross hp for the 200/229/262 are calculated but they've gotta be close:

120ghp 194i6-1v-1962-up
124ghp (gross hp) 200v6-2v-1978-79 95 net hp
V6 is No great improvement.

140ghp 230i6-1v-1963-up
155ghp 230i6-1v-"HiPerf"-1964 (wish theyda put this in 63 Nova)
145ghp 229v6-2v-1980-84 110-115 net hp
V6 is again No great improvement.

155ghp 250i6-1v-1966-up
177ghp 262v6-4v-qjet-1985-86 155 net hp
183ghp 262v6-tbi-1987-92 avg 160 net hp
So there is some gain here but v6 has:
* 12 extra inches
* A 4v or tbi
If we do that to a 250i6 the ghp will come right up there.

So surprisingly (as you noted about the low head flow) the v6 was no great improvement, just shorter and probably lighter.

What wakes it up is the Turbo!
They werent kidding about that 280 net hp Syclone, it has to make that and well over 300ghp to push that brick of a truck to 93mph.

For yours, I recall your saying once it ran maybe 104-106mph with a high of 108mph. Even assuming the 108mph was a "good weather" day, you gotta be making 450 net hp or so, near 500ghp as I'm betting on lots of losses thru the 4wd train and aero.

Any idea how much boost you're running?
Fun comparison!

Thanks for the comparisions.

My Syclone runs 108 MPH in the 1/4 last time out pretty lean (13.8 A/F ratio), it should run faster than that now.
Guessing it might run 110-112 MPH now.

The HP,, is only 396HP, it is hard to make anymore than that because the the cyl heads & the anemic camshaft it has.

I was running 25.2 PSI on the dyno & if you look @ the dyno graph it peaked out having 604 ft lbs of torque & was still making 450 ft lbs of torque @ 4500 RPM.


MBHD

Hank,
Ah, I saw that 600ftlb, just didnt know what it was, seemed too hi to be real. But I was just using a "typical" turbo map, so efficiency was lower at peak torq. Your turbo must be sized just about right so it already has full boost by peak torq. When I do that the 600+ ftlb comes right in. Falls off a little on top matching the 400hp or so you got and the timeslip lines up better now too. I think we nailed it.

And all this from that weak-looking 262-qjet engine they started with!

DeuceCoupe,

I actually get full boost before peak torque.

When I brake stall it, I will get full boost by about 2500 RPM or there abouts. I would need to review my data logs as the boost comes in so fast it is really hard to watch exactly when the full boost actually happens.

The 604 ft lbs is what it is making w/the torque multiplication of the torque converter. Then it seatles down & drops down about 450 ft lbs by max RPM 4500 w/power.

So with all the inputs you needed, what should my Syclone run next time out?

Sorry for hijacking the thread.

MBHD

That is good information to have indeed as a benchmark.
Yah weight is low I have dropped a lot of wood framing from the interior and replaced with square tubing, the net is probably even there. The 192? that was in it weighed a lot, the 250 is lighter, the fenders are gone, the suspension that is in it now is way lighter. I am still on budget for 2200# weight I actually checked the corners on the weekend, not a perfect way to do it but Rolling chasis, engine and tranny in is 1500#. Body reinforced is about 300#, a bit of interior, seats and gas tank is all that has to go in + me. I did some work there too, lost a bunch of weight this last year so shaved more horsepower requirements!