I really screwed up the engine build for my s-10 Blazer project. I had an ok 350 making around 390hp and 405lb-ft in there and it develpoed a crack in teh block so I sold it and got a 454. The 454 came out of a '97 Suburban and I had the L29 heads freshened up with a mild pocket port job and new stock sized valves. I also installed a ZZ502 roller cam and a RPM AirGap intake. I was hoping for 450-500hp. I know that it was optimistic, but I can dream right. Now here is the problem. DD2000 tells me these numbers should be true using their flow numbers for the L29 Vortec heads right from the manual it says which setting to use(450hp and 550lb-ft).

I got the actual flow data from:
http://users.erols.com/srweiss/tablehdc.htm#BBChevy

these flow numbers for the L29 are worse than the worst peanut port heads.

lift int ex
.100 63 49
.200 121 91
.300 165 120
.400 198 133
.500 226 140
.600 242 142

the small block vortecs flow more than these piles of steaming poo.
Now it appears I've built myself an expensive and slow boat anchor. With these flow numbers I'd be lucky to make 350hp@4000rpm. If I was driving a motorhome this would be great, but I have it in a 3500# street/strip car.

I ran low 13's with the small block now after spending over a year and close to $4000 I'll be back in the 14's.

What should I do?

Should I get a different set of heads like the Brodix Racerites? and live with the extremely low CR. I'm kind of stuck with a factory port location due to my custom built headers.

Should I tear it out and start over?

Do I gear it with 2 something gears and hope for the best?

I really feel stupid now...

find some small chamber large oval port heads maybe and have larger valves put in, I think Edelbrock offers heads with about 100cc chambers. ebay the boat anchor heads they should fetch some money being rebuilt.

Hehe the mistake is going to be having the BB in the s10 vs the Small Block. Time to get out the sawzall. I never read into the DTD numbers. Just trends... IE one cam vs another.

Well, if its in there and running right now, id run it to see how it goes anyways. If nothing else, you will have a good before and after comparison. Or, maybe you will be happy with it as is. As far as new heads go, a small drop in compression is worth it if you are gaining a rather large amount of airlfow. However, if we are talking about a big drop in comp, thats a different story. You might make it a bit to sloppy and it wont be fun to drive. It should still run well enough at full throttle, but it definitely wont be as much of a pleasure when your putting around. How much of a difference will it make in the comrpession? Id check into other aftermarket heads that will retain more of your compression as well as allowing you to keep your exhaust the way it is. Or, an good factory cast, old school closed chamber or semi open chamber(depending on what you need) with some good port work can run surprisingly well. Not as well as the brodix you mentioned, but if thats not in the budget than you either deal with it til you can afford the jump to an aftermarket big block head, or build a good iron head for less money and still get good results.

Those heads are listed in the SBC section, not BBC.

I generally do not find websites very credible, so I would consider it a mistake. Because the credibility, I wouldn't plan any major spending around it.

I did`nt see the heads you have listed on that link. The vortec 454 heads are very good flowing heads and will run great with the ZZ502 cam. The only draw back I`ve heard of is that there isn`t enough meat to put the bigger valves in. I was told this by a guy at Scoggin Dickey performance. Whether or not it`s true I don`t know. I say run it and see how it does. I think you`ll be surprised.

Originally posted by Twilightoptics:
Hehe the mistake is going to be having the BB in the s10 vs the Small Block. Time to get out the sawzall. I never read into the DTD numbers. Just trends... IE one cam vs another. a sawzall and a BFH...oh yeah and a few rolls of duct tape

my site (http://www.cardomain.com/id/slowride454)

I saw that listing for heads also. If not mistaken, wasn't there a 327 with a L29 designation way back?? I think those numbers are small block cyclinder head flow data. I had read info somewhere else that placed the BBC Vortec heads at about the same as traditional large oval intakes, but the exhaust was much higher. Before you do anything else, I would run it. Truthfully, I doubt 500HP is in reach, but I would bet you have a solid 425HP there along with a boatload of low & midrange torque, probably in the 520 -540 ft lb range.

500 lbs ft is the magic number! RUN IT!

The only flow test of the L-29 heads I know of was done by Salee Chevrolet and reported in a "Chevy Thunder" insert in Chevy High Performance magazine.

The exhaust port is outstanding if cleaned up. The intake port is "challenged". It will out-flow a round port BBC head if you open the valve enough.

The intake valve is so shrouded by the wall of the combustion chamber that you'd probably KILL flow with larger valves. Laying back the chamber wall might do wonders for that head.

The chamber is pretty efficient, the magazine showed about 50 ft/lb gain by retarding the timing from 32 to 30.

Even with the breathing problems, power and torque were increased from the round-port heads they replaced on the test engine.

Is that "round" as in peanut port?? or standard oval port??. Other than the vane to induce swirl in the intact port, the oval ports on the L29 vortecs are as large as any std large oval port. I would think that if the swirl inducing vane was removed or at least reduced, you would have the flow of the large ovals, but with the added benefit of the fast burn chambers and of course the nice D-Port exhausts.

Round as in peanut port. The opening to the L-29 port is large oval, but actual cc of the port is quite small-230cc or so.

what happened to CHP's website?

Trade my 350 for your 454...problem solved!

trade me your nova and chevelle for my Blazer

Can't trade the Nova...sorry.

Originally posted by Schurkey:
The only flow test of the L-29 heads I know of was done by Salee Chevrolet and reported in a "Chevy Thunder" insert in Chevy High Performance magazine.

The exhaust port is outstanding if cleaned up. The intake port is "challenged". It will out-flow a round port BBC head if you open the valve enough.

The intake valve is so shrouded by the wall of the combustion chamber that you'd probably KILL flow with larger valves. Laying back the chamber wall might do wonders for that head.

The chamber is pretty efficient, the magazine showed about 50 ft/lb gain by retarding the timing from 32 to 30.

Even with the breathing problems, power and torque were increased from the round-port heads they replaced on the test engine. where can I find this flow bench data?

February '98 CHP, in the "Chevy Thunder" section. "Heavy Lifting: Sallee Chevrolet Puts Chevrolet's Vortec Big Block Heads to the Test."

This is a comparason of the L-29 heads to some roundports, using a crate truck engine as a baseline.

Note that the flowbench data is very questionable, the exhaust ports outflow the intakes in some of comparasons. I think they screwed the pooch when they laid out the article before publishing.

You wouldn't happen to have that article somewhere? My archives only go back to '99 since I graduated college in Nov '98. If you have it is it possible to scan it?

For some reason CHP let their web address expire and now they are down.

CHP's site is up...

www.chevyhiperformance.com (http://www.chevyhiperformance.com)

I had a set of those L29's here and took a good look at them. JMHO, I would strongly consider eliminating (or at least reducing it quite bit) the cast in swirl inducer in the intake port for performance usage. The big advantage to these heads are the fast burn chambers and those D-port exhausts. Those exhausts will flow at high velocity and are the fix to the common lazy BBC heads exhaust.

Has anyone had experience with the small chamber Edelbrock heads? #60499

1. I have that article...somewhere. I looked for it yesterday and couldn't find it, and I have no idea where it went to. At any rate, it's copyrighted material.

2. You won't find that article on CHPs web site. It was included in a "special section" insert that CHP used to distribute with the magazine every other month. It was actually published by GM.

As a side note, last summer I talked to Glen Knowlton (I may have misspelled his name) of Knowlton Thunderheads. He has done work with the L-29 heads on his flowbench. I don't know where or how much he ground out of them, however. He's based in the Minneapolis area.

Very side note: for a look at the latest entry in the Oldsmobile cylinder head game, take a look at what Mr. Knowlton is working toward. The removable port sections are an incredibly clever work-around for the port shape vs. head bolt hole problems inherent in the Olds heads.

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