85ZZ4TPI

I have heard that a stock vortec head flows better than a max ported L98? True/False?

85ZZ4TPI

Im am wondering about the fast burn ones?

RoadRocket L98

Stock L98s are 155cc, out of the box Vortecs are 170cc. Needless to say, the Vortecs have more cc's, but Ive heard of L98s bein ported past 180.

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'83 Firebird 2.8
'89 Firebird Formula 350
2nd owner, red/grey, t-tops, dual cats, and a 3.27:1 rear
K&N, TB bypass, No MAF screens, CAI, full Accel ignition

Kevin91Z

iTrader: (1)

You can get a set of L98 heads to flow over 200 cfm, probably close to 220. I think the Vortec flow 220 stock. But the L98 heads flow much better on the exhaust side. Also, its a hell of a lot easier to find an intake manifold for L98 heads than Vortec heads.

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West Coast GM Shootout 2001!
1991 Camaro Z28
5.7L 5-Speed (originally 305)
13.25 @ 107.18 MPH
Southern California
Member: SoCal 3rd Gen F-Bodies
Webmaster: SoCal F-Bodies
-=ICON Motorsports=-

FlashGTA

Flow isn't everything in a cylinder head. Swirl and tumble have a lot to do with how well a head performs. A head that flows more CFM may make less power and get worse gas mileage because of a poor design which results in incomplete combustion.
When it comes to flow and swirl the Vortec's and Fast Burns are the best for performance and burn. You can get heads that flow more that will make more power, but none that will make as much power for the BTU introduced into the engine. In other words they are the most efficient.

Cntrvrsy

2 bad Lingenfelter won't release the flow #s on his ported L98s and LT1s.

RoadRocket L98

The Vortecs have 170cc intake runners and I think you could overcome the exhaust restrictions with a dual pattern favoring the exhaust side. It is a hell of a lot easier to find an L98 intake though.

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'83 Firebird 2.8
'89 Firebird Formula 350
2nd owner, red/grey, t-tops, dual cats, and a 3.27:1 rear
K&N, TB bypass, No MAF screens, CAI, full Accel ignition

DON 88T/A

L98's flow close to 200 cfm out of the box and can easily exceed 220 with smart porting,bigger valves.They have good velocity-though I thought there intake cc is around 163-165....but not sure.
Vortecs don't respond as well to porting or bigger valves,or so I've heard.

super83Z

Every time I have seen a set of Vortecs in a car mag they always have to change the valve springs. Becaust the stock ones are no good why pay for something that needs to be torn apart right away to make mild power? At least with L98's you would already have them (unless you don't and this topic is whether you are going to buy them or not) and you would save $$$; because you would port them and then get better valve springs instead of buying heads, changing valve springs, (heavily porting the exhaust side) and porting the heads.

Just go with Aluminum.

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LONG LIVE THE MUSCLE CAR!!!!! MAY ITS REIGN NEVER END

1983Z28 350w/ edelbrock performer RPM power package with 64cc aluminum heads, dynomax shorty headers, 700R-4 with shift kit, 750cfm carb, edelbrock 3" exhaust system, ASCD SS hood, 16" IROC rims.

future mods:
completely done over suspension, black paint with flames, Hurst shifter, dakota digital gauge package, procharger supercharger.

super83Z

oh yeah and I forgot the increased price for a Vortec intake. They are pretty easy to find though only if you want to go with a carb though. Good luck finding one for TPI.

Just go with Aluminum.

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LONG LIVE THE MUSCLE CAR!!!!! MAY ITS REIGN NEVER END

1983Z28 350w/ edelbrock performer RPM power package with 64cc aluminum heads, dynomax shorty headers, 700R-4 with shift kit, 750cfm carb, edelbrock 3" exhaust system, ASCD SS hood, 16" IROC rims.

future mods:
completely done over suspension, black paint with flames, Hurst shifter, dakota digital gauge package, procharger supercharger.

Kevin91Z

iTrader: (1)

The springs on the Vortec heads are good to about .460" lift or so, I'm not sure. The L98 aluminum head springs are good to about .510" lift.

And you only need to post your sig once per thread. Thanks.

Ray87Z

You can view a table w/ the flow numbers for both heads <a href="http://www.inter-scape.com/ray/headstest/headstest_4.jpg"> HERE </a>

They both flow darn near exactly the same thing on the exhaust side, w/ the Vortecs easily pulling ahead on the intake side.

If you want to run over .480-.490 lift you'll want to just buy the premodded Vortecs from Scoggin Dickey that support up to .530 or something lift I believe. They are cleareanced for that lift and have better springs. They were around $550ish for the set last I saw so still well under new AL L98 heads. I'm running .462/.469 lift on my regular stock Vortecs w/ no problems, several people are running the XE 268 cam with like .477/.480 or something for the lift on stockers w/ no problems too.

If you do a simple back cut on the exhaust valve of the Vortecs you'll up the flow around 15 cfms. It was tested in this months CHP, but I lost the stupid thing so I can't post the exact numbers. Mild porting on the Vortecs and they made a good bit more power than the ported L98s in the Goodwrench buildup articles CHP did last year I guess it was as well. Stock they pulled down more power than the pocket ported L98s in that article series. A summary of that article is online somewhere, I'll see if I can find it.

What you've heard about not-porting Vortecs is most don't advise you to home-port them beyond removing any casting flash. You can hurt velocity and flow if you don't do em right.

Of course in this situation w/ TPI you won't want the Vortecs unless the intake for them that's been on the horizon from Scoggin Dickey and others forever is finally available. I haven't heard in awhile...

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Ray87Z
-Vortec headed 350.
86 IROC w/ a cammed 305 TPI.
Formerly Ray86IROC.
www.inter-scape.com/Ray

FastBroker

Ray, are you/others running those lifts with the ORIGINAL Vortec valve springs or aftermarket springs??? Just wondering how much OEM's can take, I heard only 0.450"??!!.

Also, how much lift can they tolerate OEM before the bottom of the valve spring retainer hits the valveseal, if you happened to check??? INtake AND exhaust, pls...

farm-kid/88camaro

I emailed Jim Pace asking them if a cam would work with my stock vortec heads and this is what they replied with:

" Hello John,

It sounds like a stock replacement motor to me too. The heads will take
up to a
.480 lift and you shouldn't have a problem with the camshaft.

Thanks Mike ext#148"

So it seems thats the deal with them
hope that helped you out

Ray87Z

I'm running the stock Vortecs w/ no clearancing, with the stock springs.

Like I said several people are also running the next larger CompCams XE cam, w/ .477/.480 lift I believe it is. That should be about all you'd want to run on the stock springs, and that is pushing it a little being right at what most people accept to be the limit (.480).

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Ray87Z
-Vortec headed 350.
86 IROC w/ a cammed 305 TPI.
Formerly Ray86IROC.
www.inter-scape.com/Ray

Aaron's 87

It's all about the porter! My guy ported my early AL vette heads, put in 2.02/1.60 valves, all with a street valve job because I focused on durability. They flow just like AFR Stage 2 LT1 heads with a race valve job now. I can email the Excel graphs if anyone wants to see the results - or if someone knows how to post those graphs...

Kevin91Z

iTrader: (1)

I thought you couldnt put 2.02/1.60 valves in L98 heads, only 2.00/1.56 was the max... ??

Kevin G

I dont know about the iron L98 heads, but I have seen 250 cfm @28 inches out of a decent port job and bigger valves on the Vette heads. Nothing fully hogged out.(Cant remember the CC)


Also there really isnt much material to hogg on the Vortecs.Pretty thin walls out of the box. They are an excellent head for the money vs performance in a semi mild setup.
The only drawback is the intake for it if your runing F.I.