Where can the LT1/LT4 intakes be improved if any?
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Joined: Jun 2003
Posts: 34
It's the intake, stupid!
I've asked quite a lot of people why the LSxmotors seem to do so much better than the LTx motors, and the answer I'm most often given is "it's the intake." I'm sure there's a slight bit more to it than just that, but nearly everyone universally says the intake is the single biggest improvement over the LTx setups.
Why is that? Some possibilities:
1. The intake manifold is made out of some plastic-like material that doesn't heat up like the metal LTx intake. Cooler intake, cooler charge, more power. I would imagine it'd be possible to make an LTx intake out of the same material as the LSx intake, so we could at least get that far.
2. Different runner shape/length or different plenum volume/shape. The LSx intake obviously has a different shape and internal construction, but why couldn't that be more or less duplicated on an LTx intake? Oh, sure, the port layout and firing order is different, but does that really matter that much? Couldn't an intake be made that could closely resemble the LSx intake yet still work on the LTx motor? I find it difficult to understand why this wouldn't be possible.
3. Injector location/angle. Again, I don't see why this couldn't be replicated for an LTx motor.
The LTx motors would seem to have certain advantages over the LSx motors with the reverse-flow cooling. One would think you could run more compression with less detonation. But spend the same $$$ on the LSx engines as you do the LTx setup and the LSx motors win every time. What gives? It is the intake? The combustion chamber design? Valve size? Other than having slightly different bore and stroke setups, the LSx and LTx are very similar, certainly similar enough that I should think we could put all the good engineering on the LSx motors to work on an LTx setup.
Any comments here? What I am missing?
Why is that? Some possibilities:
1. The intake manifold is made out of some plastic-like material that doesn't heat up like the metal LTx intake. Cooler intake, cooler charge, more power. I would imagine it'd be possible to make an LTx intake out of the same material as the LSx intake, so we could at least get that far.
2. Different runner shape/length or different plenum volume/shape. The LSx intake obviously has a different shape and internal construction, but why couldn't that be more or less duplicated on an LTx intake? Oh, sure, the port layout and firing order is different, but does that really matter that much? Couldn't an intake be made that could closely resemble the LSx intake yet still work on the LTx motor? I find it difficult to understand why this wouldn't be possible.
3. Injector location/angle. Again, I don't see why this couldn't be replicated for an LTx motor.
The LTx motors would seem to have certain advantages over the LSx motors with the reverse-flow cooling. One would think you could run more compression with less detonation. But spend the same $$$ on the LSx engines as you do the LTx setup and the LSx motors win every time. What gives? It is the intake? The combustion chamber design? Valve size? Other than having slightly different bore and stroke setups, the LSx and LTx are very similar, certainly similar enough that I should think we could put all the good engineering on the LSx motors to work on an LTx setup.
Any comments here? What I am missing?
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Joined: Jun 2003
Posts: 34
Originally posted by aggiez28
i would have to dissagree.....
i would say its the heads
brook
i would have to dissagree.....
i would say its the heads
brook
Is the the chamber shape? Valve location? Spark plug location?
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Joined: Nov 1998
Posts: 71,094
From: Hell was full so they sent me to NJ
Excerpt from "The Millenium Motor: Inside the C5":
All previous, production Chevrolet V8 heads have two distinct intake and exhaust port designs. A unique feature of the LS1 head is what GM calls "replicated" ports. Each intake port is exactly same and each exhaust port is exactly the same. This eliminates combustion inconsistencies between cylinders due to variance in port flow quality and quantity.
The heads are sand cast of 356 aluminum, heat-treated to the T6 specification. Engineers use the term "valve angle" to describe the angle between cylinder bore centerline and the valve stem centerlines. It is probably the key geometrical relationship in a V8 head because it influences combustion chamber shape and size, spark plug placement, valve diameters and port design. With V-type engines, the less valve angle; the better. The LS1 angle is 15,° three less than the best of the Raceshop's Winston Cup heads and significantly below the production Small-Block’s 23°.
The LS1 intake port volume is 200 cc. which is a bit of a misnomer because of some of that volume is used for injector spray space; nevertheless, intake volume is generous. The exhaust port volume is 70 cc. The valve seat angles are 30°, 45° and 60°. The chamber roof around the valves blends smoothly with the seat’s top angle. The valves are stainless steel. The intake valve size is 2.00 in. and the exhausts are 1.55-in. with both having smaller, 8mm. valve stems. The valve face angles are 30°, 46° and 60°. The valve guides are pressed-in, sintered-iron units impregnated with material that enhances lubrication. Chamber displacement is 67.3 cc which makes for a compression ratio of 10.2:1.
The most important aspect of this head from a performance standpoint is an intake port that offers the charge air a straight shot down to the intake valve. In that respect, the difference between the intake port in the best of the old (LT4) and the first of the new (LS1) is nothing short of dramatic. We were very lucky to get to talk with the cylinder head ace himself, Ron Sperry and he said, about the design philosophy he and his team of engineers used for the intake ports, "We worked hard to make sure we had all eight cylinders as close to being identical, from a geometry standpoint, as we could. Each port is a continuous, runner-to-valve configuration. We don’t have the air turning right or left to any significant degree. There is a relatively large runner opening and it tapers down so that as (the charge air) gains speed, it’s also gaining directional stability such that the air is moving towards the valve in a very directed manner. We get the air and fuel into the cylinder with the same level of energy from bank-to-bank and port-to-port. "
Sperry added that a big enabler for the port design was packaging. By using four head bolts around each cylinder rather than the Small-Block's five, there was more room for the ports. Additionally pushrod holes, head bolt bosses and rocker arm mounting bosses were placed such that they impacted the intake ports as little as possible.
Another important feature of the LS1 intake port is it has better "injector targeting" than any Small-Block head. Injector targeting is important to idle quality and exhaust emissions. Ideally, port-injected engines should have injectors squirting a stream of fuel straight down the port, directly on the back of the hot intake valve. The temperature helps vaporize the fuel and the turbulence of the charge blowing down the port and around the valve does the rest. With the Small-Block, a straight shot at the valve was not as effective because the line running from the injector to the valve was nowhere near parallel to the port centerline. Ron Sperry: "Each port's fuel injector is targeted on the valve. We established a (port) centerline in space. The port runs back from the valve to the injector in a manner that is more linear with the injector target line."
A good cylinder head design gets the exhaust out as freely as it lets the charge in. Ron explained LS1 exhaust port philosophy, "The 15-degree angle goes a long way to fixing most of the problems we had (with the Small-Block exhaust port). The chamber is a very open design. Chamber volume is bigger than its predecessor, 54cc in the LT4 and 67cc with this engine. The 15-degree angle removes many of the short turn radius (where the port floor transitions to the valve seat) problems.
"All the surfaces are friendly in approaching the valve seat area. The valve is shrouded a bit on the bore side, but that’s about the only area there’s any restriction to getting exhaust out of the engine. We did employ the venturi-type seat that we put in the LT4 but it doesn’t have to be as drastic. The exhaust ports have some really good (flow) numbers right out of the box. They are as good as some of of the exhausts we’ve seen with modified, Bow-Tie stuff."
If you retain only one part of this discussion of the LS1 head, remember that most of this cylinder head technology goes towards one goal: increasing volumetric efficiency. If you pack more air into the cylinders, the engine makes more power. The LS1’s much better intake and exhaust port designs allow better volumetric efficiency at all engine speeds. The payoff is higher performance.
LS1's head gasket sealing is better than that of the Small-Block. The long head bolts go 88mm down into the block and have very long threads of a unique size and pitch designed for high load. They screw into threads in the case’s main web areas. The idea is to pull the sleeves and the immediate surrounding area of the decks tight against the head by exerting force at the bottom of the sleeves. An additional feature is the bolts’ length. A fastener exerts the most force when its stretched slightly and the long bolts allow a lot of material for stretching.
One final, interesting aspect of the LS1 head and deck design is that it has a negative deck-height figure. One of GMPD’s goals in combustion control was to decrease "crevice volume" which is, loosely speaking, the "squish" volume between the flat, non-chambered, part of the head exposed to the bore, plus the volume between the piston and bore above the top ring. At top dead-center, an LS1 piston top is actually 0.2mm (.008-in.) higher than the block deck and protrudes into the space surrounded by the head gasket. A typical rebuild procedure is to machine or "deck" the block to correct misalignment or lack of flatness. Once the first LS1’s need overhauls, engine rebuilder will have a learning curve with figuring out how to deck an LS1 case and preserve piston-to-head clearance.
The heads are sand cast of 356 aluminum, heat-treated to the T6 specification. Engineers use the term "valve angle" to describe the angle between cylinder bore centerline and the valve stem centerlines. It is probably the key geometrical relationship in a V8 head because it influences combustion chamber shape and size, spark plug placement, valve diameters and port design. With V-type engines, the less valve angle; the better. The LS1 angle is 15,° three less than the best of the Raceshop's Winston Cup heads and significantly below the production Small-Block’s 23°.
The LS1 intake port volume is 200 cc. which is a bit of a misnomer because of some of that volume is used for injector spray space; nevertheless, intake volume is generous. The exhaust port volume is 70 cc. The valve seat angles are 30°, 45° and 60°. The chamber roof around the valves blends smoothly with the seat’s top angle. The valves are stainless steel. The intake valve size is 2.00 in. and the exhausts are 1.55-in. with both having smaller, 8mm. valve stems. The valve face angles are 30°, 46° and 60°. The valve guides are pressed-in, sintered-iron units impregnated with material that enhances lubrication. Chamber displacement is 67.3 cc which makes for a compression ratio of 10.2:1.
The most important aspect of this head from a performance standpoint is an intake port that offers the charge air a straight shot down to the intake valve. In that respect, the difference between the intake port in the best of the old (LT4) and the first of the new (LS1) is nothing short of dramatic. We were very lucky to get to talk with the cylinder head ace himself, Ron Sperry and he said, about the design philosophy he and his team of engineers used for the intake ports, "We worked hard to make sure we had all eight cylinders as close to being identical, from a geometry standpoint, as we could. Each port is a continuous, runner-to-valve configuration. We don’t have the air turning right or left to any significant degree. There is a relatively large runner opening and it tapers down so that as (the charge air) gains speed, it’s also gaining directional stability such that the air is moving towards the valve in a very directed manner. We get the air and fuel into the cylinder with the same level of energy from bank-to-bank and port-to-port. "
Sperry added that a big enabler for the port design was packaging. By using four head bolts around each cylinder rather than the Small-Block's five, there was more room for the ports. Additionally pushrod holes, head bolt bosses and rocker arm mounting bosses were placed such that they impacted the intake ports as little as possible.
Another important feature of the LS1 intake port is it has better "injector targeting" than any Small-Block head. Injector targeting is important to idle quality and exhaust emissions. Ideally, port-injected engines should have injectors squirting a stream of fuel straight down the port, directly on the back of the hot intake valve. The temperature helps vaporize the fuel and the turbulence of the charge blowing down the port and around the valve does the rest. With the Small-Block, a straight shot at the valve was not as effective because the line running from the injector to the valve was nowhere near parallel to the port centerline. Ron Sperry: "Each port's fuel injector is targeted on the valve. We established a (port) centerline in space. The port runs back from the valve to the injector in a manner that is more linear with the injector target line."
A good cylinder head design gets the exhaust out as freely as it lets the charge in. Ron explained LS1 exhaust port philosophy, "The 15-degree angle goes a long way to fixing most of the problems we had (with the Small-Block exhaust port). The chamber is a very open design. Chamber volume is bigger than its predecessor, 54cc in the LT4 and 67cc with this engine. The 15-degree angle removes many of the short turn radius (where the port floor transitions to the valve seat) problems.
"All the surfaces are friendly in approaching the valve seat area. The valve is shrouded a bit on the bore side, but that’s about the only area there’s any restriction to getting exhaust out of the engine. We did employ the venturi-type seat that we put in the LT4 but it doesn’t have to be as drastic. The exhaust ports have some really good (flow) numbers right out of the box. They are as good as some of of the exhausts we’ve seen with modified, Bow-Tie stuff."
If you retain only one part of this discussion of the LS1 head, remember that most of this cylinder head technology goes towards one goal: increasing volumetric efficiency. If you pack more air into the cylinders, the engine makes more power. The LS1’s much better intake and exhaust port designs allow better volumetric efficiency at all engine speeds. The payoff is higher performance.
LS1's head gasket sealing is better than that of the Small-Block. The long head bolts go 88mm down into the block and have very long threads of a unique size and pitch designed for high load. They screw into threads in the case’s main web areas. The idea is to pull the sleeves and the immediate surrounding area of the decks tight against the head by exerting force at the bottom of the sleeves. An additional feature is the bolts’ length. A fastener exerts the most force when its stretched slightly and the long bolts allow a lot of material for stretching.
One final, interesting aspect of the LS1 head and deck design is that it has a negative deck-height figure. One of GMPD’s goals in combustion control was to decrease "crevice volume" which is, loosely speaking, the "squish" volume between the flat, non-chambered, part of the head exposed to the bore, plus the volume between the piston and bore above the top ring. At top dead-center, an LS1 piston top is actually 0.2mm (.008-in.) higher than the block deck and protrudes into the space surrounded by the head gasket. A typical rebuild procedure is to machine or "deck" the block to correct misalignment or lack of flatness. Once the first LS1’s need overhauls, engine rebuilder will have a learning curve with figuring out how to deck an LS1 case and preserve piston-to-head clearance.
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Joined: Jun 2003
Posts: 34
Well, I guess that just about settles it, then. I had hoped that there might be more that could be done with the LTx intake in order to make up the difference between it and the LSx motors. It appears that there really is a great deal more power in the heads than the intake (although the intake is necessary to compliment the heads). Pity, because I had hoped the reverse-flow cooling of the LTx heads could, if modified, be a better base to build on than the LSx heads. More compression, less detonation. However, it appears GM more than did their homework here.
Oh well, it just gives me one more reason to trade in my '96 Z/28 SS for a 'Vette.
Oh well, it just gives me one more reason to trade in my '96 Z/28 SS for a 'Vette.
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Joined: Jul 2000
Posts: 520
From: MD
In a nutshell, the OEM heads on the LS1 flow more and have larger ports then most ported LT1 heads. If you put a head on an LT1 that flows comparably to the LS1 head the engine will make similar power (actually, I suspect that if they are truly comparable it would actually be slightly better, but the difference would be taken up in the LT1’s heavier weight).
Does the intake design help? Some, mostly in back to back runs, since it doesn’t transfer nearly as much heat to the air flow. Is the design really superior? I don’t think so, at least for high performance use. If you look around you’ll find some _serious_ LS1/6 buildups and you’ll notice that they tend to use a sheet metal intake that is closer in design to the LT1 intake then the LS1/6 intakes (admittedly, duplicating something in the LSx style with more appropriate runner sizes is much more difficult/expensive then an LT1 style intake).
Does the intake design help? Some, mostly in back to back runs, since it doesn’t transfer nearly as much heat to the air flow. Is the design really superior? I don’t think so, at least for high performance use. If you look around you’ll find some _serious_ LS1/6 buildups and you’ll notice that they tend to use a sheet metal intake that is closer in design to the LT1 intake then the LS1/6 intakes (admittedly, duplicating something in the LSx style with more appropriate runner sizes is much more difficult/expensive then an LT1 style intake).
West South Central Moderator
Joined: Oct 2000
Posts: 3,371
From: Kilgore TX 75662
I suspect that if you put heads on the LT1 where the intake side is very close to the LS1 intake, then the LS1 would still make more power. The 15* valve angle and awesome exhaust ports have lots to do with it.
West South Central Moderator
Joined: Oct 2000
Posts: 3,371
From: Kilgore TX 75662
I've been thinking about this thread and other threads on this subject for a while now. I've got a few ideas to try when I build up my LT1. I'm sitting here looking at my spare LT1 intake, and I've got a few questions/comments. I really wish my spare heads were here instead of out in storage and I don't have any spare injectors to use to mock anything up.
1. It looks like the injector is aimed so that the fuel spray will be disrupted by the intake on the outside of the runner/injector bung. I've never watched an injector of this kind in action (I've watched TBI injectors though), so I'm not really sure about the fuel spray cone. Maybe this weekend I'll go out and grab one of those heads and see how the intake valve lines up with the injector.
How tight is the fuel spray cone?
Anyway, would you guys see a problem with changing the angle that the injector shoots toward the valve? I know this will require custom fuel rails, but that would be a given with the other modifications I'm thinking about.
I'm thinking that if I were to change the angle that injector goes into the intake, then it would give lots of room to work on the intake runner.
But now I'm thinking some more...
What is the optimum angle for the injectors to fire? Parallel to the intake runner aimed at the intake valve?
I'm not sure on how much clearance I'll have from the valve cover.. yeah, I'll go out and get one of those heads and a valve cover to see how things fit together.
1. It looks like the injector is aimed so that the fuel spray will be disrupted by the intake on the outside of the runner/injector bung. I've never watched an injector of this kind in action (I've watched TBI injectors though), so I'm not really sure about the fuel spray cone. Maybe this weekend I'll go out and grab one of those heads and see how the intake valve lines up with the injector.
How tight is the fuel spray cone?
Anyway, would you guys see a problem with changing the angle that the injector shoots toward the valve? I know this will require custom fuel rails, but that would be a given with the other modifications I'm thinking about.
I'm thinking that if I were to change the angle that injector goes into the intake, then it would give lots of room to work on the intake runner.
But now I'm thinking some more...
What is the optimum angle for the injectors to fire? Parallel to the intake runner aimed at the intake valve?
I'm not sure on how much clearance I'll have from the valve cover.. yeah, I'll go out and get one of those heads and a valve cover to see how things fit together.
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Joined: Oct 2002
Posts: 2,277
From: Orange Kounty, Kalifornia
Interesting... you could fill and re-drill the holes for the injector and cut the crossover rail. Then you could connect it with braided hose to keep it rigid and provide adequate fuel. Then you could reshape the injector port.
Do you have the means to test an injector in the manifold? Perhaps energize it with intermittant 5V blips to get the pintle to move. If you could connect some solution to the backside... like Marvel Mystery Oil, you could see where it sprays. The red color in the solution would mist on the walls.
Just throwin' ideas here...
Do you have the means to test an injector in the manifold? Perhaps energize it with intermittant 5V blips to get the pintle to move. If you could connect some solution to the backside... like Marvel Mystery Oil, you could see where it sprays. The red color in the solution would mist on the walls.
Just throwin' ideas here...
Banned
Joined: Oct 2002
Posts: 6,518
Look at the LT1 and any SBC intake closer, there is a reason that GM made the LS1 symetrical ports, because you can't get the injector to shoot at the valve really any better on a side by side port arrangement than the LT1 intake. There are packaging concerns with that intake as far as injectors go and the intake is even has the runners laid really low hurting flow to hlp with the fuel. On a single plane intake it's very hard to get good flow and optimum injector angle and placement. You would have to put the injector in the middle of the runner almost.
The LS1 intake is a awesome design in this area, those injectors shoot right at the back of the valve beause of the injector angle and the line of sight.
Just what I have seen.
Bret
The LS1 intake is a awesome design in this area, those injectors shoot right at the back of the valve beause of the injector angle and the line of sight.
Just what I have seen.
Bret
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Joined: Oct 2001
Posts: 1,462
From: smog zone adjacent to a great lake
I agree with Bret, sorta. While the injector angle is important for the reason given in Fred's above post, I believe the more important 'big picture' has been missed. The ? was asked what the optimum injector angle would be. Rereading of Fred's post will offer insight. The injector angle is superior due to the difference/change in the angle/relationship of the intake port [of head and intake plenum] to cylinder centerline. Not the other way around, where the port was left alone, and the injector angle changed.
While important, an injector angle change is 'small potatoes' compared to an intake port angle to cylinder centerline change. This would then 'kill two birds with one stone', by also improving the injector centerline to port centerline angle.
It should also be mentioned, the valve angle change improves the mixture flow characteristics entering the cylinder as well as allowing a shallower chamber roof for more compression for performance/racing use, as noted for the 18* sbc bowtie heads. The angle change is also, AFAIC, responsible, and the foundation for the superior exhaust port flow, not the port itself. With the angle of the valve changing, this results in a superior valve centerline to port centerline angle, and the short side radius can now be restructured/altered for additional flow as well.
However, on a head with an inline valve arrangement, what does this valve angle change do for the intake port? Or more to the point, what happens to the valve centerline to port centerline relationship? Taking advantage of the superior valve/cylinder centerline angle, required a raised intake port as well, just to regain the valve/port centerline relationship that the 23* head has. This is easier to visualize, when one has a mental picture of the ideal valve/port relationship. That being, the valve centeline parallel to the centerline of the port it serves. This is how I view the superiority of the LSx head.
While important, an injector angle change is 'small potatoes' compared to an intake port angle to cylinder centerline change. This would then 'kill two birds with one stone', by also improving the injector centerline to port centerline angle.
It should also be mentioned, the valve angle change improves the mixture flow characteristics entering the cylinder as well as allowing a shallower chamber roof for more compression for performance/racing use, as noted for the 18* sbc bowtie heads. The angle change is also, AFAIC, responsible, and the foundation for the superior exhaust port flow, not the port itself. With the angle of the valve changing, this results in a superior valve centerline to port centerline angle, and the short side radius can now be restructured/altered for additional flow as well.
However, on a head with an inline valve arrangement, what does this valve angle change do for the intake port? Or more to the point, what happens to the valve centerline to port centerline relationship? Taking advantage of the superior valve/cylinder centerline angle, required a raised intake port as well, just to regain the valve/port centerline relationship that the 23* head has. This is easier to visualize, when one has a mental picture of the ideal valve/port relationship. That being, the valve centeline parallel to the centerline of the port it serves. This is how I view the superiority of the LSx head.
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Joined: Mar 2001
Posts: 375
From: Glen Burnie, MD
i was talking to some people at the dyno yesterday about this and a guy from north carolina said hes seen a car make 35-40hp with a sheetmetal intake over a lt4 intake. i think he said 210 AFR's for the heads. if you look at the sheetmetal intake from moreperformance ( http://www.moreperformanceinc.com/z06.htm ) the runners are about 1.5-2" longer along with a bigger plenum and the injectrors are placed alot better.
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Joined: Oct 2001
Posts: 1,462
From: smog zone adjacent to a great lake
Originally posted by MadMaxz28
i was talking to some people at the dyno yesterday about this and a guy from north carolina said hes seen a car make 35-40hp with a sheetmetal intake over a lt4 intake. i think he said 210 AFR's for the heads. if you look at the sheetmetal intake from moreperformance ( http://www.moreperformanceinc.com/z06.htm ) the runners are about 1.5-2" longer along with a bigger plenum and the injectrors are placed alot better.
i was talking to some people at the dyno yesterday about this and a guy from north carolina said hes seen a car make 35-40hp with a sheetmetal intake over a lt4 intake. i think he said 210 AFR's for the heads. if you look at the sheetmetal intake from moreperformance ( http://www.moreperformanceinc.com/z06.htm ) the runners are about 1.5-2" longer along with a bigger plenum and the injectrors are placed alot better.
the injectors are placed alot better.
Based on what was stated in Fred's post above, and compared to oem LTx and LSx injector placement, I consider the injector placement, (actually the angle) of linked sheetmetal intake to be inferior by comparison.
I will not dispute the sheetmetal intake made/makes more power over the oem LTx intake. But I believe it adds validity to the remark I made in my above post about the injector angle advantage as being 'small potatoes' (in terms of power/torque)compared to port angle improvements. The importance of injector angle placement being for emission related issues promarily.
Last edited by arnie; Sep 12, 2003 at 06:03 PM.
West South Central Moderator
Joined: Oct 2000
Posts: 3,371
From: Kilgore TX 75662
OK, now I really see what you guys are saying. I understand it a good bit more now that I've bolted the intake to a head and got to looking at everything better.
I straightened out a coat hanger and slid it down the injector hole. From the top of that hole to the valve stem there is a distance of about 6 and a half inches. Two of those inches are in the intake manifold runner, so about four and a half inches of that is in the head. It had to go another inch to actually reach the back of the valve.
So I really don't think that there is much to gain or lose by moving the angle of the injector in the manifold...
I straightened out a coat hanger and slid it down the injector hole. From the top of that hole to the valve stem there is a distance of about 6 and a half inches. Two of those inches are in the intake manifold runner, so about four and a half inches of that is in the head. It had to go another inch to actually reach the back of the valve.
So I really don't think that there is much to gain or lose by moving the angle of the injector in the manifold...
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Joined: Jul 2000
Posts: 520
From: MD
Originally posted by Wild1
Do you have the means to test an injector in the manifold? Perhaps energize it with intermittant 5V blips to get the pintle to move. If you could connect some solution to the backside... like Marvel Mystery Oil, you could see where it sprays. The red color in the solution would mist on the walls.
Do you have the means to test an injector in the manifold? Perhaps energize it with intermittant 5V blips to get the pintle to move. If you could connect some solution to the backside... like Marvel Mystery Oil, you could see where it sprays. The red color in the solution would mist on the walls.
You’ll want to spray fluid through them that is as close to the fuel that you’re going to use as possible, any changes in viscosity will change the spray pattern and flow. You’ll also want to keep the fuel pressure close. Only use gas if you’re outside. Mineral spirits comes pretty close to duplicating gas spray pattern and being relatively safe. FWIW, water at 135psi sprayed through ford 19lb/hr injectors comes out as a stream with about 20’ range
