View Poll Results: (see below)
113's
21
53.85%
Vortec
18
46.15%
Voters: 39. You may not vote on this poll
113's Or Vortec’s
Burning Brakes
Joined: Aug 2006
Posts: 1,061
Likes: 99
From: Seattle WA
Race Director
Joined: Jun 2004
Posts: 13,961
Likes: 707
From: WI
The book mentioned above lists their ported 113 as:
Intake
.200/129.7
.300/172.8
.400/201.6
.500/224.4
.550/222.3
Exhaust
.200/108.1
.300/138
.400/162
.500/175.5
.600/176.5
The book says up to 250 cfm can be had with further work. I seem to remember some flow charts of the very expensive TPIS 113 porting in the 250 range.
The Edelbrock head above looks very nice.
Thanks for the porting ideas. I'd like to tear into these stockers some time.
Intake
.200/129.7
.300/172.8
.400/201.6
.500/224.4
.550/222.3
Exhaust
.200/108.1
.300/138
.400/162
.500/175.5
.600/176.5
The book says up to 250 cfm can be had with further work. I seem to remember some flow charts of the very expensive TPIS 113 porting in the 250 range.
The Edelbrock head above looks very nice.
Thanks for the porting ideas. I'd like to tear into these stockers some time.
Melting Slicks
Joined: May 2007
Posts: 2,382
Likes: 2
From: Kathleen FL
The only problem I see with Vortec heads is the intake bolt pattern. You would either have to redrill the heads to fit the stock pre-87 style pattern that all L98s use, or in fact redrill the intake to fit the bolt pattern of the Vortec heads. You also could have a slight problem with the spark plug interfering with the exhaust manifold because these heads don't have angled spark plug holes like the L98 has. If you got the aluminum fast burn heads and slapped them on a stock 350, the motor would be a lazy dog on torque because the velocity of the 215cc intake ports on the head would be much slower than they would be on the L98 head. If I remember correctly, the intake port size on L98 heads is a tiny 163cc and would only support at most 5500 rpms. Great on torque, but lacking much past 5500 rpms.
Pro
Joined: Jan 2008
Posts: 584
Likes: 1
From: Near Lockport NY Black 1986 Coupe
The main thing to remember about looking for a good set of heads is the numbers. Flow #s, valve size, spring size, runner volume, cc size(compression), and max lift. Shop around to find a good price on these if you can. AFR have the best flowing 180cc and 195cc heads on the market, but the price calls for it. Patriot have affordable 190cc heads on their site for $900 a pair, with flow numbers charted. Even Edelbrock and Holley have decent flow numbers. Check them out for your application, especially if you want a bigger cam!
Race Director
Joined: Jan 2008
Posts: 16,028
Likes: 170
From: oregon
this is a cool little thread & people are really being helpful with the advice. fire side chat this has become. just think over your goals, how fast you want to go will influence what head you buy. the fast burn is a better head than the 113. it is a large port but i haven't seen any problems on the dyno charts posted on the net running this head on a 350. even the GM crate has a nice torque curve. If i were debating this i would probably say.
1: edelbrock e-tec 170 or AFR 180 if you want to pony up a bit more
2. GM fast burn, not a bad choice & could be great with slight exhaust porting
3: 113 head, dated chamber and lack of flow mean lots of porting. unless you are given a pair for free the above options are much better.
don't forget the e-tec and fast burn require the vortech compatible manifold.
1: edelbrock e-tec 170 or AFR 180 if you want to pony up a bit more
2. GM fast burn, not a bad choice & could be great with slight exhaust porting
3: 113 head, dated chamber and lack of flow mean lots of porting. unless you are given a pair for free the above options are much better.
don't forget the e-tec and fast burn require the vortech compatible manifold.
Race Director
Joined: Nov 2003
Posts: 12,221
Likes: 446
From: Overland Park Kansas
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Le Mans Master
Joined: Aug 2000
Posts: 8,838
Likes: 31
From: Australia
The published numbers for 195's I have are
0.100" 51 58
0.200" 136 98
0.300" 191 136
0.400" 230 163
0.500" 253 177
0.600" 254 190
A guy over on the 3rd Gen site had some ported ;
got
266 @ 500
291 @ 600
Race Director
Joined: Nov 2003
Posts: 12,221
Likes: 446
From: Overland Park Kansas
2020 Corvette of the Year Finalist (appearance mods)
C4 of Year Winner (appearance mods) 2019
Earlier in this thread, these #s were posted. And, they're the numbers I most commonly see.
L98 113 casting (stock)
@.200 120/100
@.300 163/129
@.400 189/148
@.500 199/164
@.600 199/167
On 3rd gen, I found these numbers which look like they were directly printed from a magazine/similar regarding an 89 Corvette. (In fact, it looks like it may be the source of vaders #s and the like -- because the wording is the same on intake combinations). Anyway, these #s make the 113 castings seem even worse....
L98 113 casting (stock) 1989 from 3rd gen:
@.100 61/39
@.200 117/100
@.300 157/137
@.400 176/156
@.500 184/162
@.550 187/164 port stall point
L98 113 casting (stock)
@.200 120/100
@.300 163/129
@.400 189/148
@.500 199/164
@.600 199/167
On 3rd gen, I found these numbers which look like they were directly printed from a magazine/similar regarding an 89 Corvette. (In fact, it looks like it may be the source of vaders #s and the like -- because the wording is the same on intake combinations). Anyway, these #s make the 113 castings seem even worse....
L98 113 casting (stock) 1989 from 3rd gen:
@.100 61/39
@.200 117/100
@.300 157/137
@.400 176/156
@.500 184/162
@.550 187/164 port stall point
Melting Slicks
Joined: Jan 2008
Posts: 2,065
Likes: 1
From: Jasper Texas
I have the gmpp fast burn heads on my minirammed 85. I can't say a whole lot about them except that they have done their job.
I have read that they come from gm at peak form and should not be ported any further, can't remember where I saw this though.
If I had the money for any set of heads, I would pick brodix or afr, no doubt.
I have read that they come from gm at peak form and should not be ported any further, can't remember where I saw this though.
If I had the money for any set of heads, I would pick brodix or afr, no doubt.
Melting Slicks
Joined: Mar 2006
Posts: 2,456
Likes: 7
From: MichAgain
What about CR? 90% of the aftermarket heads need to be machined to get the CR back up because of the large combustion chamber compared to the 113's--unless you change pistons for domed ones. How much of HP diff will a 8-10 CC increase in chambers make?
Burning Brakes
Joined: Aug 2000
Posts: 1,146
Likes: 2
From: Albuquerque NM
Vortec (Al AKA fastburn) are a 50 hp bolt on increase over L98 heads
Both the vortec and fastburn require a special (0.25" like the LT4s) raised intake...
Suggest going with a AFR195 (standard CNC) and the miniram II for good flow.
Second choice ($$ limited) would be the ported L98 and the superram for good torque and fun.
Last choice would be the l98 heads and First TPI intake. At least it is sized for 350+ cubes.
Burning Brakes
Joined: Aug 2000
Posts: 1,146
Likes: 2
From: Albuquerque NM
I have the gmpp fast burn heads on my minirammed 85. I can't say a whole lot about them except that they have done their job.
I have read that they come from gm at peak form and should not be ported any further, can't remember where I saw this though.
If I had the money for any set of heads, I would pick brodix or afr, no doubt.
I have read that they come from gm at peak form and should not be ported any further, can't remember where I saw this though.
If I had the money for any set of heads, I would pick brodix or afr, no doubt.
-using undercut valves
-bowl work
-and working the short radius
I gained about 30 CFM without changing the low lift numbers
following that, I got a multi-angle valve job and shaved the heads further to 54-55 cc's
Thread Starter
Racer
Joined: Jun 2007
Posts: 367
Likes: 0
From: Springfield MA
If you dont mind how much did that set you back?
54- 55 cc how would this go with me 46k mile bottom end? would my .525 lift be an issue?
Melting Slicks
Joined: May 2007
Posts: 2,382
Likes: 2
From: Kathleen FL
.525/.525 is quite a bit high for stock L98 springs. You could use LT4 springs but even then you are still maxing them out. I'd say if you want to run the LT4 hot cam, you can 1.5 rockers and that will put you at .493/.493 lift, which is perfect for LT4 springs. Even the CC503 cam would be good as the lift on it with 1.5 rockers is .503/.510.
Race Director
Joined: Nov 2003
Posts: 12,221
Likes: 446
From: Overland Park Kansas
2020 Corvette of the Year Finalist (appearance mods)
C4 of Year Winner (appearance mods) 2019
.525/.525 is quite a bit high for stock L98 springs. You could use LT4 springs but even then you are still maxing them out. I'd say if you want to run the LT4 hot cam, you can 1.5 rockers and that will put you at .493/.493 lift, which is perfect for LT4 springs. Even the CC503 cam would be good as the lift on it with 1.5 rockers is .503/.510.
If you do dynamic compression for that cam, I suspect you're losing 1/2 to one whole compression point (compared to stock) -- because of the longer duration. I would think it would be a good match....and no problem to the bottom end.
Course any motor you "pump up" could have more potential for blow-by. But, I don't think you should worry.
Burning Brakes
Joined: Aug 2007
Posts: 915
Likes: 0
From: salinas ca
I know it hasn't been mentioned but check out the patriot heads, also i would stay away from TF heads. There was a norcal forum member who bought some tf heads that destroyed his motor, I don't remember the whole story but they were a$$holes about it and would not do anything about it. Just my .02