What needs to be done when converting 18* Heads to fit our block?
Thread Starter
Registered User
Joined: Oct 2000
Posts: 440
From: Albuquerque,NM--5,600 feet above you sea-level cats
What needs to be done when converting 18* Heads to fit our block?
Just wondering. Whould Brodix work. It just seems I can only go so far with the 23* head our motors come with and if It's not to hard to fit a 18* head on I will probably sell my GTP 210's and go that route. Looking to get the most power I can out of this Solid Roller 396.
Registered User
Joined: Dec 2001
Posts: 43
From: KS
You didn't say what kind of engine, but pistons will need to be changed for correct valve reliefs. Headers will be different and most require an offset lifter on the intake lobe. Brodix has a head that uses std 23 degree valvetrain I.E. std rockers valve covers, lifters, and etc. If I remember right it's the 18x head. they flow around 325cfm out of the box.
If this is a all out race engine you should look at some sb2.2 heads. They poduce the same torque curve as a 18 degree but will make around 30 to 50 hp more on the top end. The real problem is (as with any large cc heads) to get the large power numbers you need to use a cam in the 260 degree at .050 and up. When you have a cam of this size unless the compression is way up there the engine won't have the low or mid-range it should. The engine with usually be very peaky. This is very noticable on the dyno. I messed with several and if you can't put alot of compression in it (at least 14 to 1) you wont be very happy. You can back the cam down but the power figures go down pretty fast.
One note if looking at sb2.2 heads the intake cc is deceiving. most sb2.2 are in the 280 to 290 cc range this is compairable to a 250ish 18 degree head because the runner is longer on the sb2.2 head.
If this is a all out race engine you should look at some sb2.2 heads. They poduce the same torque curve as a 18 degree but will make around 30 to 50 hp more on the top end. The real problem is (as with any large cc heads) to get the large power numbers you need to use a cam in the 260 degree at .050 and up. When you have a cam of this size unless the compression is way up there the engine won't have the low or mid-range it should. The engine with usually be very peaky. This is very noticable on the dyno. I messed with several and if you can't put alot of compression in it (at least 14 to 1) you wont be very happy. You can back the cam down but the power figures go down pretty fast.
One note if looking at sb2.2 heads the intake cc is deceiving. most sb2.2 are in the 280 to 290 cc range this is compairable to a 250ish 18 degree head because the runner is longer on the sb2.2 head.
Registered User
Joined: Mar 2001
Posts: 49
From: Park Ridge, IL
I've been running 18* heads on my street engien for the last 2 years. You're definitely right, you can easily make alot more power and torque witht he significantly increased flow of the 18* heads vs. 23* heads. Besides the increase in flow across the valve lift range, the combustion chambers are also more efficient than most 23* heads, allowing you to make more power with less ingition advance.
Most 18* heads are also raised port, and spread port, so you will probably need new headers. The Brodix heads are a nice compomise between 18* and 23*, giving you almost as much flow while still using 23* valvetrain. True 18* heads like I use will require offset, shaft mounted rocker arms from Jesel, T&D, or Crower. You'll also need offset lifters and custom pushrods. Additionally, you'll need either a modified intake manifold or 18* intake manifold because the intake ports are also raised and relocated compared to 23* heads. Also due to the revised valve locations and angles, 18* pistons are needed.
You'll also want to consider running an auxillary cooling line from your water pump to the cylinder head between the two siamesed exhaust ports. This will ensure adequate cooling to this area which is susceptible to head gasket failure due to the higher heat and pressure at that point. While not necessary, it's an easy and effective preventative measure.
Here's a complete and detailed description of all the differences...http://www.montygwilliams.com/cylinderheads.html
Most 18* heads are also raised port, and spread port, so you will probably need new headers. The Brodix heads are a nice compomise between 18* and 23*, giving you almost as much flow while still using 23* valvetrain. True 18* heads like I use will require offset, shaft mounted rocker arms from Jesel, T&D, or Crower. You'll also need offset lifters and custom pushrods. Additionally, you'll need either a modified intake manifold or 18* intake manifold because the intake ports are also raised and relocated compared to 23* heads. Also due to the revised valve locations and angles, 18* pistons are needed.
You'll also want to consider running an auxillary cooling line from your water pump to the cylinder head between the two siamesed exhaust ports. This will ensure adequate cooling to this area which is susceptible to head gasket failure due to the higher heat and pressure at that point. While not necessary, it's an easy and effective preventative measure.
Here's a complete and detailed description of all the differences...http://www.montygwilliams.com/cylinderheads.html
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Joined: Oct 2002
Posts: 2,931
From: Upstate NY
This is actually SStrokerAce
PNYKILR,
As Monty said the valve train is all custom for it. On top of that convering a 18 deg to a LT1 takes alot of machine work, but it can be done. For 325cfm heads you might as well buy a set of 215RR heads, they need the shaft mounts just like a 18 deg head. I would look into good CNC ported 18 deg heads if you are going to go that far anyways. I'd also go work with someone who can build this for you since there are alot of things different in this setup.
If it's for a tradtional small blockwhy just stick with 18 deg heads. All Pro has a bunch of good heads that flow crazy that are already set up to revearse cool on a Gen I SBC.
Monty,
You have the Aqua vette, with the turbo small block and the single plane on it? That engine was the precursor to the Chicayne engine right? What's the intake on your car? It's a Super Vic for 18 deg heads right? I like the pleanum setup you guys did, and the larger volume is needed for the turbo setup.
Your right about the cooling lines going between the middle exhaust ports. That's a sprint car trick, probably needed in a turbo street engine too.
Bret
PNYKILR,
As Monty said the valve train is all custom for it. On top of that convering a 18 deg to a LT1 takes alot of machine work, but it can be done. For 325cfm heads you might as well buy a set of 215RR heads, they need the shaft mounts just like a 18 deg head. I would look into good CNC ported 18 deg heads if you are going to go that far anyways. I'd also go work with someone who can build this for you since there are alot of things different in this setup.
If it's for a tradtional small blockwhy just stick with 18 deg heads. All Pro has a bunch of good heads that flow crazy that are already set up to revearse cool on a Gen I SBC.
Monty,
You have the Aqua vette, with the turbo small block and the single plane on it? That engine was the precursor to the Chicayne engine right? What's the intake on your car? It's a Super Vic for 18 deg heads right? I like the pleanum setup you guys did, and the larger volume is needed for the turbo setup.
Your right about the cooling lines going between the middle exhaust ports. That's a sprint car trick, probably needed in a turbo street engine too.
Bret
Thread Starter
Registered User
Joined: Oct 2000
Posts: 440
From: Albuquerque,NM--5,600 feet above you sea-level cats
Thanks for the replies. I just thought there were a few on here that are running different heads on there LT1. It was just a thought, and was not sure if it could be done. I just wish we had the choise the LS1 guy's have(15* head). I'm just hoping to come close to 500rwhp NA. The motor is almost done. The car is a M6-
12.5.1 396LT1
Flat top piston with 8cc vavle
6" rod
Calies Drangon slayer crank
Solid roller cam from D. Elgin Racing Cams(250/256 @.050 644/614 lift
AFR 210's ported by GTP
Intake/Exhaust
.200--153.4/103.5
.300--209.1/157.9
.400--254.6/195.7
.450--269.6
.500--281.5/221.6
.550--291.8/227.6
.600--299.3/231.7
.650--306.0/233.6
.700--310.5/235.9
12.5.1 396LT1
Flat top piston with 8cc vavle
6" rod
Calies Drangon slayer crank
Solid roller cam from D. Elgin Racing Cams(250/256 @.050 644/614 lift
AFR 210's ported by GTP
Intake/Exhaust
.200--153.4/103.5
.300--209.1/157.9
.400--254.6/195.7
.450--269.6
.500--281.5/221.6
.550--291.8/227.6
.600--299.3/231.7
.650--306.0/233.6
.700--310.5/235.9
Registered User
Joined: Aug 2000
Posts: 556
From: Chicago, IL
SStrokerAce....
no, that was john meany's vette. Monty's motor is modeled after it
www.montygwilliams.com
no, that was john meany's vette. Monty's motor is modeled after it
www.montygwilliams.com
Registered User
Joined: Mar 2001
Posts: 49
From: Park Ridge, IL
Bret,
As Jimmy pointed out, the car you are referring to is John Meany's C4 TT Corvette. My Corvette does have a TT 427 as well, very similar to Meany's, and I did model my turbo system after his. The Meany/Trepanier team produces what I think is the ultimate combination of power, reliability and beauty. I saw Chicayne a few weeks ago at the WOW show and it is indeed an amazing display of knowledge, creativity and attention to detail.
I had already built a NA SBC 427 that made 650hp on 93 octane and put about 500 miles on it when I saw Meany's car on PHR TV and in PHR almost a year and a half ago. I had always wanted to do a TT setup, but after seeing his, I was convinced to do it immediately. The following Monday I ordered turbos and wastegates and started planning the buildup. I just changed the cam and pistons and built the turbo system around the engine I already had. Meany and I do use the same model Dart block (although he stays with a stock deck height and 400ci while I use a taller 9.325" deck block with a 4.00" stroke for 427ci) and heads but he has a custom manifold based off of a single plane, while I just had Hogan's make one for me to fit my requirements. My cam is also wider than his. I run a 254/254 on a 115LSA, and I believe his cam is 230/239, 114LSA. My cam goes against conventional turbo cam wisdom in that it's got more overlap and duration than what you typically see, but I still feel that larger displacement engines need more duration, as well as the fact that my Dart CNC Gen II 18* heads are very efficient and have pretty good balance between the intake and exhaust ports.
As Jimmy pointed out, the car you are referring to is John Meany's C4 TT Corvette. My Corvette does have a TT 427 as well, very similar to Meany's, and I did model my turbo system after his. The Meany/Trepanier team produces what I think is the ultimate combination of power, reliability and beauty. I saw Chicayne a few weeks ago at the WOW show and it is indeed an amazing display of knowledge, creativity and attention to detail.
I had already built a NA SBC 427 that made 650hp on 93 octane and put about 500 miles on it when I saw Meany's car on PHR TV and in PHR almost a year and a half ago. I had always wanted to do a TT setup, but after seeing his, I was convinced to do it immediately. The following Monday I ordered turbos and wastegates and started planning the buildup. I just changed the cam and pistons and built the turbo system around the engine I already had. Meany and I do use the same model Dart block (although he stays with a stock deck height and 400ci while I use a taller 9.325" deck block with a 4.00" stroke for 427ci) and heads but he has a custom manifold based off of a single plane, while I just had Hogan's make one for me to fit my requirements. My cam is also wider than his. I run a 254/254 on a 115LSA, and I believe his cam is 230/239, 114LSA. My cam goes against conventional turbo cam wisdom in that it's got more overlap and duration than what you typically see, but I still feel that larger displacement engines need more duration, as well as the fact that my Dart CNC Gen II 18* heads are very efficient and have pretty good balance between the intake and exhaust ports.
Monty,
You have the Aqua vette, with the turbo small block and the single plane on it? That engine was the precursor to the Chicayne engine right? What's the intake on your car? It's a Super Vic for 18 deg heads right? I like the pleanum setup you guys did, and the larger volume is needed for the turbo setup.
Your right about the cooling lines going between the middle exhaust ports. That's a sprint car trick, probably needed in a turbo street engine too.
Bret [/B]
You have the Aqua vette, with the turbo small block and the single plane on it? That engine was the precursor to the Chicayne engine right? What's the intake on your car? It's a Super Vic for 18 deg heads right? I like the pleanum setup you guys did, and the larger volume is needed for the turbo setup.
Your right about the cooling lines going between the middle exhaust ports. That's a sprint car trick, probably needed in a turbo street engine too.
Bret [/B]
Registered User
Joined: Mar 2001
Posts: 49
From: Park Ridge, IL
I've yet to see anyone, anywhere successfully use those 32 valve heads. Those things have been around for awhile, previously under the Dominion brand, but I've never actualy seen or heard anyone that had them, not even in any magazine articles?
Registered User
Joined: Feb 2000
Posts: 1,009
From: Cincinnati, OH, USA
My guess is that they, like other "wild" heads like 18* (for LT1), do require extensive mods like have been discussed already: custom headers, intake, etc.
Probably since the reason people would consider such heads in the first place is to make massive power, no one wants to risk splitting the LT1 block at the power levels one could acheive with them. So they move on to SB1 blocks, where one can get heads cheaper than the Araos. That's my guess.
It is a shame that there is no first-hand experience that can be shared with us, I agree.
Solomon
Probably since the reason people would consider such heads in the first place is to make massive power, no one wants to risk splitting the LT1 block at the power levels one could acheive with them. So they move on to SB1 blocks, where one can get heads cheaper than the Araos. That's my guess.
It is a shame that there is no first-hand experience that can be shared with us, I agree.
Solomon
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Joined: Nov 2001
Posts: 2,985
From: In a house by the bay
PNYKILLR,
What kind of power are you looking to make?
It's easier to make the power with a race head but it's not a necessity. The heads I'm running are 15 degree (a rolled 18 degree head). Nothing like the LS head but the valve is 15 degrees. You could go with a splayed valve head... the GM 517. Those are 16/11 degree (I/E) with a 4 degree cant. Or you could go with the SB2.2 (I have a set for sale complete with titanium valves).
The question is the power. How much and how much rpm? You can make 700+ hp with 23 degree heads, even on big small blocks (427 ci+).
-Mindgame
What kind of power are you looking to make?
It's easier to make the power with a race head but it's not a necessity. The heads I'm running are 15 degree (a rolled 18 degree head). Nothing like the LS head but the valve is 15 degrees. You could go with a splayed valve head... the GM 517. Those are 16/11 degree (I/E) with a 4 degree cant. Or you could go with the SB2.2 (I have a set for sale complete with titanium valves).
The question is the power. How much and how much rpm? You can make 700+ hp with 23 degree heads, even on big small blocks (427 ci+).
-Mindgame
Registered User
Joined: Nov 2001
Posts: 2,985
From: In a house by the bay
Solomon,
The LT block can take more than you can throw at it n/a. I'm making ~650 crank horsepower with a 383, 15 degree heads and a 6600 rpm peak. Tough to make that kind of power with such a low rpm peak but that's what I was after and thats why I went with this cylinder head.
-Mindgame
The LT block can take more than you can throw at it n/a. I'm making ~650 crank horsepower with a 383, 15 degree heads and a 6600 rpm peak. Tough to make that kind of power with such a low rpm peak but that's what I was after and thats why I went with this cylinder head.
-Mindgame
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Joined: Feb 2000
Posts: 1,009
From: Cincinnati, OH, USA
Mindgame,
Those numbers are... respectable.
Very nice.
I guess I am assuming that generally the "max power out of the LT1 block" crowd goes FI of some type, whether boost or spray, which generally would push one close to or past the limits of the block.
From what I've seen on here, people tend to think that building a max-power N/A LT1 block isn't as cost effective as SBC, after all is said and done.
What custome parts did your head setup require? Headers, intake, etc.? I myself am looking for a good N/A setup that can be sprayed, so please share what you can.
Solomon
Those numbers are... respectable.
Very nice.I guess I am assuming that generally the "max power out of the LT1 block" crowd goes FI of some type, whether boost or spray, which generally would push one close to or past the limits of the block.
From what I've seen on here, people tend to think that building a max-power N/A LT1 block isn't as cost effective as SBC, after all is said and done.
What custome parts did your head setup require? Headers, intake, etc.? I myself am looking for a good N/A setup that can be sprayed, so please share what you can.
Solomon
Registered User
Joined: Nov 2001
Posts: 2,985
From: In a house by the bay
Solomon,
A good deal of this engine was put together by Chuck Riddeck. He chose the cam specs and had a custom grind made. He also performed all the porting and valve work on the 15 degree heads, along with the reverse-cool-modifications. Chuck is an R&D engineer and is somwhat secretive about his work.
I am still waiting to hear back with him and promised to keep much of the information on the "down low". I don't think Chuck will mind, but I would like to get the man's ok before I start running my mouth. Too late huh?
Some things I can say:
I used the LT4 intake, which was prepared by a local race engine builder. Chuck built the heads for use with an intake like the Vic jr, but since I had the intake for $80 (core cost) I went ahead with the project. There were quite a few modifications to make everything work but the shop in question is used to this level of work. The internals are nothing extraordinary. The pistons are reverse dome BME's (combustion chambers are 44 cc's) and static compression is 11.8:1. I'm using FAST for engine management but that's only because I may want to turn things up a notch later on...... I never rule that possibility out.
The biggest part of this type of job is in the machine work, but it can be done on a bit of a budget if you don't feel the need to use billet parts everywhere. Maybe more on this later.
-Mindgame
A good deal of this engine was put together by Chuck Riddeck. He chose the cam specs and had a custom grind made. He also performed all the porting and valve work on the 15 degree heads, along with the reverse-cool-modifications. Chuck is an R&D engineer and is somwhat secretive about his work.
I am still waiting to hear back with him and promised to keep much of the information on the "down low". I don't think Chuck will mind, but I would like to get the man's ok before I start running my mouth. Too late huh?
Some things I can say:
I used the LT4 intake, which was prepared by a local race engine builder. Chuck built the heads for use with an intake like the Vic jr, but since I had the intake for $80 (core cost) I went ahead with the project. There were quite a few modifications to make everything work but the shop in question is used to this level of work. The internals are nothing extraordinary. The pistons are reverse dome BME's (combustion chambers are 44 cc's) and static compression is 11.8:1. I'm using FAST for engine management but that's only because I may want to turn things up a notch later on...... I never rule that possibility out.
The biggest part of this type of job is in the machine work, but it can be done on a bit of a budget if you don't feel the need to use billet parts everywhere. Maybe more on this later.
-Mindgame