I just picked up a set of vette heads for $385 shipped. How much better do these flow over stock L98 heads? I think i will need new springs too but I am not sure which ones to get. I was thinking of getting the LT4 springs because they are cheap. I also want to use the LT4 hot cam because it is cheap too. With 1.6 rockers and the cam is that going to be too much for otherwise stock corvette heads?

James

------------------
If the women don't find you handsome they should at least find you handy
Aftermarket T-56 (pain in the A$S but worth it)
Lots of things to do still

 

I ALSO JUST GOT A SET OF THESE HEADS.
MINE WHERE $421 SHIPPED FROM TABER CORVETTE PARTS, WHERE DID YOU GET YOURS?
I'M PUTTING LT4 SPRINGS IN THEM, VALVE JOB, AND GOING TO DO A LITTLE PORTING.
THEY ARE SUPPOSED TO FLOW BETTER THAN CAST, THE PORTS I THINK ARE A LITTLE DIFFERENT DESIGN. BUT THE SAVED WEIGHT IS THE GOOD PART, I SWEAR THEY ARE SO LIGHT COMPARED TO MY FRIEND'S IRON HEADS!

------------------
88 CAMARO RS
87 IROC-Z DRIVETRAIN
305 TPI, 700R4, 3.73s
ported plenum, performance resource chip,edelbrock TES Headers and cat-back, K&Ns, AFPR, rest is stock.
15.0 @ 92.5 (bald tires)

 

OH YA,
I'VE HEARD THESE HEADS RESPOND VERY WELL TO PORTING, LIKE YOU CAN GET 40 HP JUST FROM A GOOD PORT JOB.
TELL ME HOW IT GOES.

 

I recently help a friend do some work on his 87 Vette, which should have the same heads you guys are talking about. I sold him some 1.6 roller tip rockers I used on my L98 cast iron heads, and when we went to install them, they were too long - the tips were off the valve stem. It appears that the Vette heads use a specific rocker, unless there was something else we overlooked. Just wanted to pass that along.

 

I dunno what you guys did, but I used the same 1.52 and 1.65 roller rockers on my iron heads and my L98 aluminum heads.

Fake-Iroc, please dont post in all caps.

There is a little blurb in the latest edition of Car Craft, in the Ask Marlon section. He tells you what you should do when porting the L98 heads.

------------------
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=-

 

I have no interest in porting theses heads. I got them as a cheap upgrade to my stock heads. I want to loose weight and get a small bit of power. I am getting a miniram, cam and throttle body soon and I hope to get a good 50-70 horse from these 4 things and my 1.6 rockers. What about springs. Are LT4 springs too much for stock vette heads?

James

 

I agree with kevin... the rockers should have worked. Maybe there was a problem with pushrod length or the locks.

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Black 90 IROC, L98, A4, 323 gear. SuperRamed 406 in the works!

 

You will see a HUGE gain if you port those heads. They pretty much suck stock. They dont flow a whole lot of air for a modded 350 engine.

The LT4 HOT cam springs are fine, as GM uses these same heads on the ZZ4 engines with LT4 HOT cam springs.

 

OK not in caps, sorry.
i just got my heads today. they look great!
the LT4 springs are in and the builder said that they are good to about .500 lift on the vette heads.
what lift is your cam going to be, mine is .480 & .480. you might need more than the LT4 springs if your intended lift is alot.
About the 1.6 roller rockers, on some heads you have to elongate the pushrod hole towards the intake manifold, or the rocker won't be on the vavle right. this is only on certain heads, check before you put them on.
i've heard drilling out the hole is pretty easy though with a tool from summit.
i'm going with 1.5 roller rockers, i don't think that my 305 will be needing the added lift with the new cam.

 

[About the 1.6 roller rockers, on some heads you have to elongate the pushrod hole towards the intake manifold, or the rocker won't be on the vavle right. this is only on certain heads, check before you put them on.
i've heard drilling out the hole is pretty easy though with a tool from summit.
NEVER MIND THIS PART. i was thinking of something else.

 

I really like the vette heads, a quick pocket port, debur the chamber, and remove the casting *uglies* in the chamber and have fun. You will nedd to have the appropriate calibration thou. They like alot more timing in cruise, and a lot less at WOT.
I've had a couple cars that I tweaked on run best with just 28-32d of total timing. Then small chambers work well

 

Nobody has answer the original question yet. How much better are these heads stock when it comes to flow compared to the stock L98 iron heads? I want numbers

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'88 GTA 350
Headers, catback, free mods, Xtreme energy cam, and intake pieces
13.51@104.27, but can run better as it is.

I just put a new 2100-2300 RPM TQ Converter. I hope a 13.20 or better

RAPTOR, the baddest bird on the planet
AIM HIGH!

 

Stock the aluminum L98 heads flow 196 cfm on the intake and 159 cfm on the exhaust, at .500 lift. With some porting they get up to 220 intake and 180 exhaust.

I dont have anything on the iron L98 heads.

 

The Corvette heads have similar flow #s to the stock heads on the intake side without any portwork. The main gain is on the exhaust side, the D shaped exhaust port flows considerably better than the stock square ports do.
As I remember these heads, although they do not post big top flow #s, outflow just about everything else at lower lifts, which is of course where our engines spend most of their time.
Roy

 

Roy's analysis is correct. Here's the flow #'s in CFM measured @ 28" water for stock heads measured on the same flow bench.

Corvette Aluminum # 113
Lift/Intake/Exhaust
.100 62 49
.200 116 98
.300 161 130
.400 185 152
.500 195 159

350 Cast Iron # 083
Lift/Intake/Exhaust
.100 44 41
.200 101 82
.300 155 125
.400 182 137
.500 196 140

The better low lift flow of the AL heads yields 10-20 more HP in Dyno 2000 sims compared to the iron heads.

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89 Formula 350, Accel Tri-Ys, 3" SLP, chip, Jacobs, SLP cold air, Probuilt tranny, Vigilante, 3.27s, Spohn torque arm & LCAs w/brackets, GW Subs

 

I still wouldn't buy me these heads unless they were DIRT cheap and new. After you have them ported by a pro, the price will climb pretty close to or even more that aftermarket heads. I'll save my money for TrickFlows or Edelbrock.
Anyone using Trick Flows? How you like 'em?

------------------
'88 GTA 350
Headers, catback, free mods, Xtreme energy cam, and intake pieces
13.51@104.27, but can run better as it is.

I just put a new 2100-2300 RPM TQ Converter. I hope a 13.20 or better

RAPTOR, the baddest bird on the planet
AIM HIGH!

 

Something else, people on this board and many other places keep talking about torque and low end power. Unless you plan on being a loser all your life, you MUST aim for higher RPM power (I'm not talking about 10 000 RPMs, but something in the 5500-6500 RPM range). Power below 5000 RPMs aint gonna cut it no more in this high revving world. That's why many of US (including me) get stomped by 300ZX's and Supras. By the time we shift at 4700 RPMs, not only has the turbos flown by, but we are falling back down to 3500 RPMs. Don't believe me? Look at TRAXIONs engine. A high revving engine (easily 6000 RPMs if not more) and as far as I know, He is the most succesful of all of us.
I myself have ported SLP runners, Edelbrock base, 58mm TB and stock iron heads; I know this setup is not enough to stay on top and I won't be on top until I change this (cam is pretty big though). In the meantime I have to be happy with my 13.50@104, which is better than many of you out there, in case you want to call me a loser. Once again, you MUST aim for a higher RPM band (don't go overboard!) if you are to be competitive out there.

I don't mean to hurt anybody's feeling with this reply, but we need to wake up from the dream that torque is king and is gonna win us races and face reality.
Good day everybody

------------------
'88 GTA 350
Headers, catback, free mods, Xtreme energy cam, and intake pieces
13.51@104.27, but can run better as it is.

I just put a new 2100-2300 RPM TQ Converter. I hope a 13.20 or better

RAPTOR, the baddest bird on the planet
AIM HIGH!

 

Oooh, that's why those little riceburners with no torque always woop me
For real though, I have beaten cars on the street that might take me in the quarter because I have the low and midrange torque and that's what gets used on the street.

 

Oooh, that's why those little riceburners with no torque always woop me
For real though, I have beaten cars on the street that might take me in the quarter because I have the low and midrange torque and that's what gets used on the street.
---------------------------------------------------------------

And your times are??????????

I bet you are the kind of guy who owns a V8 and are used to picking on Honda and Yugo guys. I don't know about you or the others, but I have come accross 280ZXs and had to go home with my head down. Once raced an LT5 and it looked as if the guy had hit the afterburners at 40 MPH. I saw a 454 chevelle get ran over by a 280ZX. My boss owns an MR2 Turbo and with a simple Home Depot trick that we did, now runs 14.3@97 MPH on an otherwise STOCK engine; way faster than many of us here.
Once again, high revving cars. If you want to keep denying it, FINE! I believe my best strategy is to know what the competition runs and learn from them.

By the way, you speak like that at your local rice gathering and somebody WILL put you to shame. I have seen a Civic running 12.49 sec on a fogger system.
The all mighty V8 is not so mighty anymore, we better get ready for what's coming!

Rick, all american muscle lover

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'88 GTA 350
Headers, catback, free mods, Xtreme energy cam, and intake pieces
13.51@104.27, but can run better as it is.

I just put a new 2100-2300 RPM TQ Converter. I hope a 13.20 or better

RAPTOR, the baddest bird on the planet
AIM HIGH!

 

Hey Raptor
I didnt say a thing about low RPM power and neither did anybody else. What I talked about was flow at low lift levels, which is not the same thing at all. Everybody wants to compare head flows at .550 lift, and what most guys dont seem to understand is that even with a high lift cam, you still spend twice as much time at .250 lift than at .550 lift. What I said was that the vette heads outflow most other heads at low lift levels. Matter of fact take the #s on the vette heads and on some of the hot aftermarket stuff and add em up at every .50 or so of lift. Now total the overall flow you get over the entire lift range. The vette heads will flow much closer overall #s than are indicated if you just pick a high lift point on the various heads and say see, these XYZs flow way more at 550 lift! Pretty archaic comparison but you see the point. Who gives a **** what they flow at .550 or .600 lift. Even the big cam guys are only there for a few degrees of duration and then they are back heading toward those low lift levels again. Flow at low lift levels has nothing to do with RPMs. But what it does have to do with is how much mixture gets in overall thruout one full stroke. So do I think the vette heads are the greatest available? Nope, but if you pick up a set for $400 and port em yourself, they are pretty darn good for the price.
BTW challenge one of those hot ricers to a roll on in high gear at 1500 RPM and you will once again remember what the mighty V-8 engines are all about.
Roy

 

Roy,
After reading your original post, I must admitt that I missunderstood your post. You are right, you never mentioned anything about RPMs, HOWEVER, my point is still valid and true.
There is nothing more dissapointing than having a car that will melt the tires, but takes a nose dive at 4700 RPMs because it just can't breathe. TPI cars are this way, they feel like a Mack truck, lots of torque, but no power to make them go fast. Cars need torque for take off (especially automatic), but after that, it's all about POWER

By the way, the rolling start option when racing a turbo might be your worst decision. If you do this, you will give your opponet a head start by letting him spool up his turbo and get out of his weakest point which is down low in the RPM band (torque remember, they ain't got none, so are better off racing "rolling start")

 

Roy
I admitt that I misunderstood your post. You are right, you never mentioned anything about RPMs, however, the point I made is true and valid. There is nothing more dissapointing than having a car that can melt tires, but takes a nose dive after 4700 RPMs if not before that; TPI cars are like Mack trucks, lots of torque, but no horsepower. I have raced Turbo cars and sometimes I was able to pull 1-2 cars ahead from the hole, but when the turbo started doing it's thing, the other car would gain on me very fast and eventually win the race. All cars need torque to get them moving (especially automatic), but after that it's all about horsepower.

BTW, if you race a Turbo on a roll on, you are giving your opponent a head start. Turbos need to spool up to make power and torque. They are the weakest out of the hole since they have to go from a standing still.

 

What the hell????

 

Where did you get these heads for $385? I assume that means complete. Or was this a private party deal?

------------------
87 IROC 350, 3:42 Torsen
13.94@103mph, 2.25 60'
Stock cam, chip and trans
In the works: ported SLP runners, ported base, Xtreme Cam, homemade suspension pieces, and 27x10 Hoosiers.
Hoping for 12.999

 

Slight correction, done right lag is a none issue nowadays with a EFI setup (for a street car). Anyway you want to slice it, I can be well into boost at 2500 rpm., weither just flashing the converter from a stand still or downshifting on a roll. As a routine I let folks leave on me, and I leave easy so I don't blow the tires off.
I've got the drivetrain as a 89 TTA and can set one of those up the same way, just to keep this all 3rd gen TPI specific.
Torque or HP takes a whole package to do that.
Splitting the two takes alot of effort and both ends suffer, to some degree.

 

I picked them up complete from this guy. I think I am going to have them ported and polished with a 3 angle valve job so I can get the maximum potential out of the miniram.

James

 

Slight correction, done right lag is a none issue nowadays with a EFI setup (for a street car). Anyway you want to slice it, I can be well into boost at 2500 rpm., weither just flashing the converter from a stand still or downshifting on a roll. As a routine I let folks leave on me, and I leave easy so I don't blow the tires off.
I've got the drivetrain as a 89 TTA and can set one of those up the same way, just to keep this all 3rd gen TPI specific.
Torque or HP takes a whole package to do that.
Splitting the two takes alot of effort and both ends suffer, to some degree.

You are right Grumpy, most newer turbo cars don't have the turbo lag problem anymore, which makes them even harder to keep up with.
BTW, what do you run with your 89 Turbo T/A? I heard somewhere that the 250 HP rating from GM was way below of what they really make; I heard somewhere else that they could run low 13s in completely stock form. What was your best time stock?
Thanks, Rick

 

i hear ya on that one.....the TPI unit on a stock engine is a pretty good design but once u start modding the engine and increasing the power the stock TPI just doesn't cut it.....time to upgrade the intake
------------------
89 GTA
Originating memeber of the SJNEP crew
Rice....it's whats for dinner
check out the car here:
http://www.hometown.aol.com/clarkemustgonow

Tony

[This message has been edited by fly89gta (edited November 27, 2000).]

 

Consider this:
Lingenfelter offers these heads in there 383 crates...putting out 430-460hp.
Tpis sells them as well.
For the money they are excellent-
Also they have a smaller cc chamber than the iron L98,supporting more compression....
Alot of people spend big $$ on AFR'S,and while they are proven,you can achieve most desired results with the L98
aluminums...I have a portd set of L98 aluminums that flow 235 cfm with the stock 1.94 valve...I'm now stepping up to the 2.00 valve...as is,they flow as well if not better than the edelbrocks out of the box with bigger 2.02 valves....

The only draw back to these heads are they don't have much material in the deck (compared to AFR'S)thus you can't go over board with a power adder...

And they don't over the porting potential of aftermarket heads...
But like I said these heads will support an 11 second car...on motor.

 

 

Okay....didnt mean to do that....

 

For the price they want for ported L98 heads (which I think is about $1500 from either LPE or TPIS) I can get me Trick Flows, AFR, Canfield or Eldelbrock. Not only are all these heads better because they have nore meat for serious engines, you can also port them and have flow well beyond ported L98's.

I think if you can get a pair of aluminum L98 heads dirt cheap and have a buddy (or yourself) do the porting dirt cheap, then they are worth it; if the total price (heads and porting) is more than $750 (which I really doubt you can find that kinda deal) then in my opinion, it's just a waste of time and money.
Rick

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'88 GTA 350
Headers, catback, free mods, Xtreme energy cam, intake pieces and 2100 RPM TQ

*13.40@102.55 MPH* <--- Best New ET
1.90 Sec, Best 60FT
104.23 MPH, Best Trap Speed

 

I said ligenfelter offers them on there 383's to show they can be used on bigger motors.....I got mine cheap,as could anyone,and did get a good deal on porting.

 

I have a set of the vett heads I was going to have a three angle valve job done on them $100 and buy a set of the stainless valves theat SDPC has on sale for$79 and then use the port polish kit from eastwood $24 I bought the heads and the base to go with them for $550 so I only would have had almost $800 in to the heads and base by the time I was done.But could have saved $ by not getting the new valves.Any Whay I had a set of fast burn heads given to me and that is what I will use now. so if any one would like to try them I will sell the heads and base for 550 and i will ship them or if SDPC gets there TPI base for vortec heads any time soon I will trade every thing for one of those bases.

 

To answer the original question with a slight twist, On the engine below, when it was stock, I added fully ported Vette heads that had been milled .015, polished fully ported exhaust and the bowls had been cleaned up. Except for the addition of a flowmaster, this was the only mod that I did. I went from a 14.6 to a 14.1 and gained 5 mph.

It's good to see all those TEXAS guys out there. Beware of the lil 305 cop car lurking around the corner, because if you think she was fast as a 305/5spd, what di you think she'll be like as a 357/5spd.


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1992 Texas DPS B4C 1LE FE2 5.0/5spd:
Intake and Plenum Ported
Fully Ported Corvette Heads
TPIS Tricks ,No Smog Pump, NOS FI Fuel Pump
K&N's Adj. Fuel Pressure Regulator
Alston SFC's, Energy Supension Hyperflex system
MSD 6AL, SLP 1 3/4" SS Headers
3.73's with 275/55/16's out back...blew those now 2.73 one legger
My complete back seat
encompases my RF tunes...

Currie 9" on the way with 3.70 gears

Adam