LT1 heads on an L98
12-21-2002, 04:39 PM
#51
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Here are some more ramblings.
I just read a couple of articles on the reverse cooling system of
the LT1 engine and the advantages it gives.
The "normal" cooling sytem like the L98 sends coolant into the
block first which they say runs the cylinders at a cooler than
optimum temperature. Then the already heated coolant goes into
the head which allows them to run at a higher than optimal
temperature. This design allows the cylinders to run at a cooler
temperature than the heads which the articles state promotes
piston ring wear from the cooler cylinders and detonation from the
hotter heads.
The LT1 system Flows the coolant into the head first to regulate
them at an ideal temperature then into the block to raise the
cylinders to an ideal temperature. This is designed to keep the
heads and the cylinders at as close to the same temperature as
possible. The LT1 water pump also pulls the coolant from the block
rater than push it into the block. The coolant is pulled from the
block and pushed into the lower connection of the radiator totally
opposite of an L98 system. The coolant then flows up through the
radiator and back to the thermostat housing from the upper hose
connection. The thermostat is a 2 stage bypass system which
maintains constant coolant flow through the block and meters
how much coolant is allowed into the engine from the radiator.
A pretty simple system which allows the LT1 to run more timing
and higher compression on regular pump gas than an L98 engine.
I am thinking we can use an older V-belt style water pump which
will pull coolant from the block because our serpentine belt setup
will spin it backwards. It will bolt on and work with our pulleys and
create a reverse coolant flow. Next, run the upper radiator hose
to the remote thermostat housing and lines from it to the rear of
each head. Now we need to create a bypass to get hot coolant
to the thermostat to open it as needed. Some of the early style
water pumps for V-belt applications had a heater hose return hole
in the top of them which would provide a spot for coolant to exit
as the water pump was spun backward. This connection could be
routed to the heater core then to the remote thermostat housing
to provide hot coolant to the thermostat.
This setup would work similar to the LT1 setup in that hot coolant
would be drawn from the block via an older style water pump
which was spinning in reverse. A portion of the hot coolant would
flow into the heater core and back to the thermostat housing and
then evenly divided into the back of each head where it will cool
the heads first then flow into the block to cool the cylinders then
back out through the water pump and back on to the heater core.
When the coolant temperature became hot enough the
thermostat would open and allow the water pump to push coolant
backwards from the radiator through the thermostat and on it's
way to the back of the heads.
The thermostat will cool quite rapidly and close sooner than
normal which will raise it's cycle rate and possibly maintain the
engine at a more constant temperature.
Wala, reverse cooling with LT1 heads and intake on an L98 block.
I just read a couple of articles on the reverse cooling system of
the LT1 engine and the advantages it gives.
The "normal" cooling sytem like the L98 sends coolant into the
block first which they say runs the cylinders at a cooler than
optimum temperature. Then the already heated coolant goes into
the head which allows them to run at a higher than optimal
temperature. This design allows the cylinders to run at a cooler
temperature than the heads which the articles state promotes
piston ring wear from the cooler cylinders and detonation from the
hotter heads.
The LT1 system Flows the coolant into the head first to regulate
them at an ideal temperature then into the block to raise the
cylinders to an ideal temperature. This is designed to keep the
heads and the cylinders at as close to the same temperature as
possible. The LT1 water pump also pulls the coolant from the block
rater than push it into the block. The coolant is pulled from the
block and pushed into the lower connection of the radiator totally
opposite of an L98 system. The coolant then flows up through the
radiator and back to the thermostat housing from the upper hose
connection. The thermostat is a 2 stage bypass system which
maintains constant coolant flow through the block and meters
how much coolant is allowed into the engine from the radiator.
A pretty simple system which allows the LT1 to run more timing
and higher compression on regular pump gas than an L98 engine.
I am thinking we can use an older V-belt style water pump which
will pull coolant from the block because our serpentine belt setup
will spin it backwards. It will bolt on and work with our pulleys and
create a reverse coolant flow. Next, run the upper radiator hose
to the remote thermostat housing and lines from it to the rear of
each head. Now we need to create a bypass to get hot coolant
to the thermostat to open it as needed. Some of the early style
water pumps for V-belt applications had a heater hose return hole
in the top of them which would provide a spot for coolant to exit
as the water pump was spun backward. This connection could be
routed to the heater core then to the remote thermostat housing
to provide hot coolant to the thermostat.
This setup would work similar to the LT1 setup in that hot coolant
would be drawn from the block via an older style water pump
which was spinning in reverse. A portion of the hot coolant would
flow into the heater core and back to the thermostat housing and
then evenly divided into the back of each head where it will cool
the heads first then flow into the block to cool the cylinders then
back out through the water pump and back on to the heater core.
When the coolant temperature became hot enough the
thermostat would open and allow the water pump to push coolant
backwards from the radiator through the thermostat and on it's
way to the back of the heads.
The thermostat will cool quite rapidly and close sooner than
normal which will raise it's cycle rate and possibly maintain the
engine at a more constant temperature.
Wala, reverse cooling with LT1 heads and intake on an L98 block.
12-21-2002, 07:41 PM
#53
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Car: 84 SVO
Engine: Volvo headed 2.3T
Transmission: WCT5
Axle/Gears: 8.8" 3.73
Originally posted by Swapmaster
I am thinking we can use an older V-belt style water pump which
will pull coolant from the block because our serpentine belt setup
will spin it backwards. It will bolt on and work with our pulleys and
create a reverse coolant flow. Next, run the upper radiator hose
to the remote thermostat housing and lines from it to the rear of
each head. Now we need to create a bypass to get hot coolant
to the thermostat to open it as needed. Some of the early style
water pumps for V-belt applications had a heater hose return hole
in the top of them which would provide a spot for coolant to exit
as the water pump was spun backward. This connection could be
routed to the heater core then to the remote thermostat housing
to provide hot coolant to the thermostat.
I am thinking we can use an older V-belt style water pump which
will pull coolant from the block because our serpentine belt setup
will spin it backwards. It will bolt on and work with our pulleys and
create a reverse coolant flow. Next, run the upper radiator hose
to the remote thermostat housing and lines from it to the rear of
each head. Now we need to create a bypass to get hot coolant
to the thermostat to open it as needed. Some of the early style
water pumps for V-belt applications had a heater hose return hole
in the top of them which would provide a spot for coolant to exit
as the water pump was spun backward. This connection could be
routed to the heater core then to the remote thermostat housing
to provide hot coolant to the thermostat.
12-21-2002, 10:23 PM
#54
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Car: 91 Camaro Z28
Engine: 5.7 TPI
Transmission: T-56
So would using the coolant lines in the back of the head w/ a remote t-stat cause any problems because it wouldnt be flowing backwards like in the LT1 engines?
Or would it just flow like the L98 so there would be no additional risk?
Basically I just want to know if the LT1 head setup would put extra wear or stress on the engine.
Or would it just flow like the L98 so there would be no additional risk?
Basically I just want to know if the LT1 head setup would put extra wear or stress on the engine.
12-22-2002, 01:09 AM
#55
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Using the outlets in the back of the heads to plumb to a remote
thermostat housing is the only option if you use the LT1 heads
and intake together. It would work functionally the same as doing
the LT1 intake swap only with L98 heads. The LT1 heads are not
that different from L98 heads, just the coolant ports that need to
be modified.
The direction of flow doesn't really matter, it's just that the LT1's
reverse cooling is more efficient allowing you to run a lot more
timing and a bit more compression by cooling the heads better.
thermostat housing is the only option if you use the LT1 heads
and intake together. It would work functionally the same as doing
the LT1 intake swap only with L98 heads. The LT1 heads are not
that different from L98 heads, just the coolant ports that need to
be modified.
The direction of flow doesn't really matter, it's just that the LT1's
reverse cooling is more efficient allowing you to run a lot more
timing and a bit more compression by cooling the heads better.
12-22-2002, 12:44 PM
#56
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http://h-body.org/people/projects/bu...t1%20info.html
Here is a link to an LT1 cooling article if anyone is interested.
Here is a link to an LT1 cooling article if anyone is interested.
12-22-2002, 04:31 PM
#57
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Car: 91 Camaro Z28
Engine: 5.7 TPI
Transmission: T-56
Swapmaster when are you planning on doing this swap? I am going to do it also but wont be able to until May (when I graduate college after 5 short years
).
I am interested in finding out how well it works before I become the first guinea pig. 86 Iroc did it but I dont think he actually ever ran the motor. I have the LT1 heads and intake already just have to get both modified and put on.
).I am interested in finding out how well it works before I become the first guinea pig. 86 Iroc did it but I dont think he actually ever ran the motor. I have the LT1 heads and intake already just have to get both modified and put on.
12-22-2002, 09:02 PM
#58
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I will have the motor together and in a car by spring. I am going
with the cast iron heads with some mild port work. GM did away
with the reverse cooling in 97 because of problems with steam
and air pockets getting trapped in the heads causing hot spots
in the combustion chambers so the reverse flow is out and normal
flow is back in. I think there needs to be water outlets drilled into
the front of the heads into the highest part of the water jackets
to continuosly keep any air bled off. If you will notice, the engine
sits in the car at a slight angle, a little higher at the front. This is
what they were having problems with, air getting trapped in the
front-most top of the water jacket of the heads. I am going to
study this for a bit more but think that drilling a 1/2" bleed hole
into the front of each head and bringing them together to feed
the heater core may be an option. Trying to run coolant from the
LT1 heads to the LT1 intake is just not possible unless you make
you own intake gaskets.
I will have the heads Tuesday and will be able to set the heads
and intake on a block to scope things out a little closer.
with the cast iron heads with some mild port work. GM did away
with the reverse cooling in 97 because of problems with steam
and air pockets getting trapped in the heads causing hot spots
in the combustion chambers so the reverse flow is out and normal
flow is back in. I think there needs to be water outlets drilled into
the front of the heads into the highest part of the water jackets
to continuosly keep any air bled off. If you will notice, the engine
sits in the car at a slight angle, a little higher at the front. This is
what they were having problems with, air getting trapped in the
front-most top of the water jacket of the heads. I am going to
study this for a bit more but think that drilling a 1/2" bleed hole
into the front of each head and bringing them together to feed
the heater core may be an option. Trying to run coolant from the
LT1 heads to the LT1 intake is just not possible unless you make
you own intake gaskets.
I will have the heads Tuesday and will be able to set the heads
and intake on a block to scope things out a little closer.
Last edited by Swapmaster; 12-22-2002 at 09:04 PM.
12-23-2002, 09:07 AM
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Car: 1988 Camaro IROC-Z
Engine: 350 TPI (L98)
Transmission: T56
Axle/Gears: 9-bolt 3.45
What about the reverse spinning water pumps. You can find them at Jegs and Summit.
12-23-2002, 10:05 AM
#60
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I looked around but could not find a pump to draw coolant out of
the block. The only way to do it wold be to take the impeller out
of the pump so it couldn't pump anything and install an electric
water pump to flow the system backward. Electric pumps are
expensive though, like $400 for one that would work for us.
But then there are issues with air getting trapped in the system.
Normally air is trapped in the radiator because the coolant flows
from the top to the bottom and the air gets trapped in the top
and only coolant makes it into the engine from the bottom. With
reverse flow the coolant will flow from the bottom to the top and
any air will keep being drawn back into the engine through the
top radiator hose. You would need a pressurized overflow bottle
like that used in an LT1 system to keep air out of the engine.
Not impossible but it can get complex trying to do it with a remote
thermostat housing. Problem is that you need to flow hot coolant
to the remote thermostat to get it to open and also have lines
going to a pressurized bottle which could cause a cluster fuc* of
hoses running all over the place if not planned out carefully.
the block. The only way to do it wold be to take the impeller out
of the pump so it couldn't pump anything and install an electric
water pump to flow the system backward. Electric pumps are
expensive though, like $400 for one that would work for us.
But then there are issues with air getting trapped in the system.
Normally air is trapped in the radiator because the coolant flows
from the top to the bottom and the air gets trapped in the top
and only coolant makes it into the engine from the bottom. With
reverse flow the coolant will flow from the bottom to the top and
any air will keep being drawn back into the engine through the
top radiator hose. You would need a pressurized overflow bottle
like that used in an LT1 system to keep air out of the engine.
Not impossible but it can get complex trying to do it with a remote
thermostat housing. Problem is that you need to flow hot coolant
to the remote thermostat to get it to open and also have lines
going to a pressurized bottle which could cause a cluster fuc* of
hoses running all over the place if not planned out carefully.
12-23-2002, 10:23 AM
#61
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If you look at this picture, you will see next to the top accessory
holes next to the intake I have drawn two black circles. I am
thinking of drilling and tapping fittings into these spots to run
bleed tubes to a pressurized overflow bottle.
holes next to the intake I have drawn two black circles. I am
thinking of drilling and tapping fittings into these spots to run
bleed tubes to a pressurized overflow bottle.
12-23-2002, 11:04 AM
#62
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Car: 1988 IROC-Z
Engine: L98 (350 TPI)
Transmission: MD8 (700 R4) + 3.42 LS1 Rear
i wish i had the time and extra$$$ to do this. i would have done/tried it already. i've always thought about doing this. i too have disliked all the hoses all over the place with the LT1 intake conversion. it makes the engine bay look "cluttered and unorganized". this would be a somewhat cheaper alternative since LT1 heads+intakes are plentiful. if someone can get this to work this would be fukin great 
Great work swapmaster.
i commend you for trying this feat. keep up the good work.:hail:
Great work swapmaster.
i commend you for trying this feat. keep up the good work.:hail:
12-23-2002, 11:38 AM
#63
Originally posted by Swapmaster
The LT1 water pump also pulls the coolant from the block
rater than push it into the block. The coolant is pulled from the
block and pushed into the lower connection of the radiator totally
opposite of an L98 system. The coolant then flows up through the
radiator and back to the thermostat housing from the upper hose
connection.
The LT1 water pump also pulls the coolant from the block
rater than push it into the block. The coolant is pulled from the
block and pushed into the lower connection of the radiator totally
opposite of an L98 system. The coolant then flows up through the
radiator and back to the thermostat housing from the upper hose
connection.
Re-read my post here as well as
my posts in this thread.
The LT1 Y/B/D/F radiators flows DS to Passenger Side, just like any 3rd gen F-body V8 Gen I SBC radiator. Grab both hoses as the car warms up and say otherwise
Secondly, the water isn't pulled, it's pushed. The water is pushed into the block on any LT1. The thermostat element opens and closes based on the temp of the outgoing water (which goes from block to upper radiator hose.) But, the thermostat controls the incoming water.
The thermostat is a 2 stage bypass system which
maintains constant coolant flow through the block and meters
how much coolant is allowed into the engine from the radiator.
A pretty simple system which allows the LT1 to run more timing
and higher compression on regular pump gas than an L98 engine.
maintains constant coolant flow through the block and meters
how much coolant is allowed into the engine from the radiator.
A pretty simple system which allows the LT1 to run more timing
and higher compression on regular pump gas than an L98 engine.
I am thinking we can use an older V-belt style water pump which will pull coolant from the block because our serpentine belt setup will spin it backwards. It will bolt on and work with our pulleys and create a reverse coolant flow.
My next question though, is with what you're talking about, you plan on exiting the water from the back of Gen II cylinder heads. Well, since a water pump on a Gen I SBC pushed water into the block, if you exit it out the cylinder heads at the rear, you're not going to cool the front of the heads for a darn.
The best idea here so far that hasn't been documented and done is the std. water pump (or reverse rotation for serpentine,) and exit the water from the tapped locations in the front of the heads. Read my post above in this thread for two minor pitfalls of that.
Matthew
12-23-2002, 10:53 PM
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I'm just kicking ideas around here basically thinking out loud.
Just looking for the best way to go about doing this and possibly
using the reverse cooling aspect if possible.
jmd, what are your thoughts given the fact that when using LT1
heads and intake together you can not pass coolant from the
heads to a modified intake with coolant nipples added to it
either in the front or the rear very easily.
You could use the coolant outlet in the front of the passenger
side head but not on the drivers side head because the bracket
for the alternator covers that spot.
Oh, also there is a bolt hole that does not line up on the A/C
bracket. The A/C bracket has two bolts that go into the head, the
bolt closest to the water pump has no boss in the head to screw
into. You will need to drill and tap a hole but the jacket material
is real thin in that spot, REAL thin, not a big deal though.
Pulling the coolant from the back of the head will actually cool the
engine more evenly. How many engines have you had with the
number 8 or 7 piston reforged and shrunken because the back
of the engine ran a lot hotter than the front of the engine. I have
had 4 such shrunken pistons on 4 different engines through the
years, 5 actually, my Jaguar currently has a shrunken piston in
the number 8 hole from running a tad warm a few times. It has
never overheated but has been warm a few times, enough to
overheat the piston and cause piston slap when cold.
I know a few circle track guys who have exited the coolant from
the back of the intake to combat overheating the rear of the
engine. So that is a proven sollution that does work. Millican puts
the coolant outlets in the rear of his LT1 intakes now and nobody
is having a problem as of yet so that is a viable sollution.
This is a discussion board so let's figure this out. I'm just looking
at all possibilities. They may or may not work, but in the end
something will.
Just looking for the best way to go about doing this and possibly
using the reverse cooling aspect if possible.
jmd, what are your thoughts given the fact that when using LT1
heads and intake together you can not pass coolant from the
heads to a modified intake with coolant nipples added to it
either in the front or the rear very easily.
You could use the coolant outlet in the front of the passenger
side head but not on the drivers side head because the bracket
for the alternator covers that spot.
Oh, also there is a bolt hole that does not line up on the A/C
bracket. The A/C bracket has two bolts that go into the head, the
bolt closest to the water pump has no boss in the head to screw
into. You will need to drill and tap a hole but the jacket material
is real thin in that spot, REAL thin, not a big deal though.
Pulling the coolant from the back of the head will actually cool the
engine more evenly. How many engines have you had with the
number 8 or 7 piston reforged and shrunken because the back
of the engine ran a lot hotter than the front of the engine. I have
had 4 such shrunken pistons on 4 different engines through the
years, 5 actually, my Jaguar currently has a shrunken piston in
the number 8 hole from running a tad warm a few times. It has
never overheated but has been warm a few times, enough to
overheat the piston and cause piston slap when cold.
I know a few circle track guys who have exited the coolant from
the back of the intake to combat overheating the rear of the
engine. So that is a proven sollution that does work. Millican puts
the coolant outlets in the rear of his LT1 intakes now and nobody
is having a problem as of yet so that is a viable sollution.
This is a discussion board so let's figure this out. I'm just looking
at all possibilities. They may or may not work, but in the end
something will.
12-23-2002, 10:54 PM
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Oh, what do you guys think of the idea of putting bleed holes into
the front of the heads up high near the intake? I think this is a
must do item. Use two AN# 6 elbows and bring them together
into a T with an AN# 12 outlet to run to the heater core. Then run
the heater core outlet to a T which is connected to the extra
outlet from the remote thermostat which will go to the heater
hose return nipple in the radiator. This will run coolant to the
heater core, allow hot coolant to run past the thermostat and
direct both flows to the return in the radiator.
the front of the heads up high near the intake? I think this is a
must do item. Use two AN# 6 elbows and bring them together
into a T with an AN# 12 outlet to run to the heater core. Then run
the heater core outlet to a T which is connected to the extra
outlet from the remote thermostat which will go to the heater
hose return nipple in the radiator. This will run coolant to the
heater core, allow hot coolant to run past the thermostat and
direct both flows to the return in the radiator.
Last edited by Swapmaster; 12-23-2002 at 11:15 PM.
12-24-2002, 01:36 AM
#66
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Car: IROC Z
Engine: 355 MINIram w/boost
Transmission: T56
this swap thing sounds interesting, BUT, why? isnt the intake swap enough? arent there aftermrkt heads that flow as well as LT1 heads at close to the same price considering all the time in research and developement? help me understand the importance of this swap? i like it, i just need more reason to want to do it myself. is it the challenge at hand? good luck to all, I do think it will work!
12-24-2002, 07:37 AM
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Because for a few hundred dollars you can have a set of heads
that are capable of producing in the 500HP range instead of over
a grand for some aftermarket aluminum heads.
And besides, someone said it couldn't be done. Therefore it will.
that are capable of producing in the 500HP range instead of over
a grand for some aftermarket aluminum heads.
And besides, someone said it couldn't be done. Therefore it will.
12-24-2002, 03:28 PM
#70
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Car: IROC Z
Engine: 355 MINIram w/boost
Transmission: T56
thats what i thought. thats ("it cant be done") the same reason why i made an 88-92 S/C work on my 86 v belt, not as complicated as this project, but i understand the feeling! sweeeet!
04-30-2003, 09:34 PM
#71
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Car: 91 TA vert
Engine: 355
Transmission: T5
has anyone tackled this yet with the intake and heads and a success, i am about to have my heads machined and send my intake to john to be modified....
05-01-2003, 12:51 AM
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I almost bought an engine a couple years back off a guy from Jersey that had this head and intake conversion done. He was running a stock bottom end with arp rod bolts, and trw forged pistons with heavily ported lt1 heads and intake. Together with a very mild cam it ripped off mid elevens N/A, and high nines with a 200 shot in a full weight third gen.
From some of the comments I heard about this guys car, it idled like a stocker, and won many a bet.
From some of the comments I heard about this guys car, it idled like a stocker, and won many a bet.
05-01-2003, 09:23 AM
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Car: 91 TA vert
Engine: 355
Transmission: T5
well this is my only worry, my cam has:
an advertised duration of 284/292
duration at .050 222/230
lift is .509/.528
and with the Lt1 heads i will have to have them shaved...bottom end is stock L98 for the time being until i am able to build a new bottom end, valves i will measure today if i can find the micrometer and im wondering how much im going to have them shaved...valves if they are stock size i will have them cut for 2.00 and 1.56, screw in studs, guideplates, cut for larger springs, ported and polished...just not sure the size of the valves...and also using the Lt1 intake with the heads....
an advertised duration of 284/292
duration at .050 222/230
lift is .509/.528
and with the Lt1 heads i will have to have them shaved...bottom end is stock L98 for the time being until i am able to build a new bottom end, valves i will measure today if i can find the micrometer and im wondering how much im going to have them shaved...valves if they are stock size i will have them cut for 2.00 and 1.56, screw in studs, guideplates, cut for larger springs, ported and polished...just not sure the size of the valves...and also using the Lt1 intake with the heads....
07-02-2003, 02:40 PM
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As a thought to the whole reverse flow coolant thing, I don't know what the flow rating of a water pump is, but couldn't we use a high flow electric fluid pump to pump the fluid whichever direction we want?
Or - what about using a LT1 electric water pump w/ modifications? No cam drive to worry about being electric.
Or - what about using a LT1 electric water pump w/ modifications? No cam drive to worry about being electric.
07-02-2003, 05:17 PM
#77
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Car: 1999 Z28
Engine: LS1
Transmission: 6 Speed
Axle/Gears: 9" 4.11 Truetrac
besides the reverse flow cooling of the LT1 heads which will be fun to convert on a reg. sbc. what advantages do they have over the corvette aluminum L98 heads?
07-03-2003, 09:08 PM
#79
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The aluminum LT1 heads flow about the same as the aluminum L98 heads, but the cast iron LT1 heads flow way more (230 intake), even out flowing the Vortec heads. The advantage to reverse cooling is that the heads run way cooler allowing more compression and timing with lower octane gas. But I have come to the conclusion that the cast LT1 heads will never work on an L98 motor, it's just not possible to convert the water passages. Eventualy I will use an LT1 block without the optispark and use the manifold John modded for me with the cast LT1 heads and MAP setup with a distributor. Been so damn busy though that I have not had a chance to get the car out of storage yet this year. It's been tucked away for going on 9 months now.
THIS SUCKS, I WANT TO BEAT MY CAR.
THIS SUCKS, I WANT TO BEAT MY CAR.
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