New Injectors and Throttle Body???
Thread Starter
Staging Lane
Joined: Dec 2013
Posts: 55
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New Injectors and Throttle Body??? I'm in the process of having the top-end of my 92 LT-1 engine rebuilt. That is, I'm adding headers, new ported cylinder heads, bigger camshaft, roller rockers, etc. My question is whether it is critical to also replace the stock fuel injectors and throttle. My engine builder told me the stock items are in good condition and that upgrading them would not yield a noticeable power increase for a street-only daily driver. He has some concerns with the existing water pump and Optispark and thinks my money will be better spent replacing these items now while the engine is out of the car. He explained that the labor cost to replace the injectors and throttle body at some point in the future will be considerably less than the labor to replace the pump and distributor when the engine is back in the car. What do you guys think?
My concern here is that you are just asking these questions now rather than before starting the "build".
I would put a cap and rotor on the opti and replace the waterpump. People treat the opti as a single unit, it is a distributor with cap and rotor that are tuneup items like any other distributor.
Far as labor to change the TB and injectors later, well that gives me a LOT of reason for concern about your build in general. You need tuning for these mods and if it needs bigger injectors which it likely would with any decent heads/cam setup then it requires retuning for that, especially the 92 ECM because that is less able to adapt and store feedback changes than the 94+ systems. That retuning will be a lot harder to accomplish than a waterpump swap.
The TB is easy to swap later and on a 92 setup might not need reprogramming and if the guy think s this will be OK on 20+yo 22lbs injectors then either the engine is so mild it wont need a larger TB of the guy is clueless. Honestly I fear it a combination of the two.
If you can give us a list of engine specs we can better tell you if an injector upgrade is likely necessary.
I would put a cap and rotor on the opti and replace the waterpump. People treat the opti as a single unit, it is a distributor with cap and rotor that are tuneup items like any other distributor.
Far as labor to change the TB and injectors later, well that gives me a LOT of reason for concern about your build in general. You need tuning for these mods and if it needs bigger injectors which it likely would with any decent heads/cam setup then it requires retuning for that, especially the 92 ECM because that is less able to adapt and store feedback changes than the 94+ systems. That retuning will be a lot harder to accomplish than a waterpump swap.
The TB is easy to swap later and on a 92 setup might not need reprogramming and if the guy think s this will be OK on 20+yo 22lbs injectors then either the engine is so mild it wont need a larger TB of the guy is clueless. Honestly I fear it a combination of the two.
If you can give us a list of engine specs we can better tell you if an injector upgrade is likely necessary.
Thread Starter
Staging Lane
Joined: Dec 2013
Posts: 55
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The install will include Trick Flow top-end kit TFS-K304-430-400 along with headers, 3.73 gears and 2500 rpm converter. No mods to the bottom end. It's intended to be a mid-level performance upgrade for what will be a street-only daily driver. The specs on the cam are:
Duration at 050 inch Lift: 220 int./227 exh.
Advertised Intake Duration: 266
Advertised Exhaust Duration: 272
Advertised Duration: 266 int./272 exh.
Intake Valve Lift with Factory Rocker Arm Ratio: 0.530 in.
Exhaust Valve Lift with Factory Rocker Arm Ratio: 0.530 in.
Valve Lift with Factory Rocker Arm Ratio: 0.530 int./0.530 exh.
Lobe Separation (degrees): 113
Duration at 050 inch Lift: 220 int./227 exh.
Advertised Intake Duration: 266
Advertised Exhaust Duration: 272
Advertised Duration: 266 int./272 exh.
Intake Valve Lift with Factory Rocker Arm Ratio: 0.530 in.
Exhaust Valve Lift with Factory Rocker Arm Ratio: 0.530 in.
Valve Lift with Factory Rocker Arm Ratio: 0.530 int./0.530 exh.
Lobe Separation (degrees): 113
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TECH Veteran
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OP
the kit, including the fasteners for heads and gasket set is a decent $. Some would argue that a H/C combo from Advanced Induction or Lloyd Elliott would yield more power than the TF kit. If you took that direction the costs to include all the stuff that is in TF kit would be more (gaskets, fasteners, RR)
To comment on your ? about WP & Opti vs injector/TB upgrade...I would replace the Cap & Rotor with a MSD Cap/Rotor kit and get a "new" WP.
If your engine builder is not a "qualified tuner of LT1 motors" I would contact someone like Ed Wright or other known tuners and ask about the merits of larger injectors & TB for "your" build. Your motor will require a tune regardless of weather you get larger injectors/TB or not (it will require adjustments for all)
I suspect larger injectors would be recommended but stock TB may be good for the cam size you have. again discuss with a tuner
take note of the head gasket thickness of the gaskets in the TF kit, your chamber size and how far your pistons are in/out of the hole for compression ratio. Maybe a Victor .028 head gasket would be better.....
the kit, including the fasteners for heads and gasket set is a decent $. Some would argue that a H/C combo from Advanced Induction or Lloyd Elliott would yield more power than the TF kit. If you took that direction the costs to include all the stuff that is in TF kit would be more (gaskets, fasteners, RR)
To comment on your ? about WP & Opti vs injector/TB upgrade...I would replace the Cap & Rotor with a MSD Cap/Rotor kit and get a "new" WP.
If your engine builder is not a "qualified tuner of LT1 motors" I would contact someone like Ed Wright or other known tuners and ask about the merits of larger injectors & TB for "your" build. Your motor will require a tune regardless of weather you get larger injectors/TB or not (it will require adjustments for all)
I suspect larger injectors would be recommended but stock TB may be good for the cam size you have. again discuss with a tuner
take note of the head gasket thickness of the gaskets in the TF kit, your chamber size and how far your pistons are in/out of the hole for compression ratio. Maybe a Victor .028 head gasket would be better.....
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Brett Foote If you want advise, my advise is ask questions BEFORE you commit this deeply to a mistake.
Can you fix any of this? Guessing not since you are stressing about replacing the opti and WP Vs. injectors.
The converter is a big labor to change item you are doing very wrong.
Can you fix any of this? Guessing not since you are stressing about replacing the opti and WP Vs. injectors.
The converter is a big labor to change item you are doing very wrong.
Thread Starter
Staging Lane
Joined: Dec 2013
Posts: 55
Likes: 0
If you want advise, my advise is ask questions BEFORE you commit this deeply to a mistake.
Can you fix any of this? Guessing not since you are stressing about replacing the opti and WP Vs. injectors.
The converter is a big labor to change item you are doing very wrong.
Can you fix any of this? Guessing not since you are stressing about replacing the opti and WP Vs. injectors.
The converter is a big labor to change item you are doing very wrong.
. I do think upgrading to the manual version's 3.45 gears would make it much more lively, and you have to get it tuned anyway 
I would replace the WP and cap and rotor as mentioned if the opti is otherwise in good shape, (optical sensor portion not corroded, no play in the drive shaft....they can and do wear out) the WP's on seem to go bad between 60-90K in my experience with the LT1. Also, consider upgrading to an electric WP, and gain ~10HP with better cooling. Thread Starter
Staging Lane
Joined: Dec 2013
Posts: 55
Likes: 0
Thread Starter
Staging Lane
Joined: Dec 2013
Posts: 55
Likes: 0
That is a small emissions friendly cam, I see no reason why you can't run the stock converter.....not to mention this is a 3200lb Corvette, not a 4200lb land yacht B-body 96Capricemgr is used to . I do think upgrading to the manual version's 3.45 gears would make it much more lively, and you have to get it tuned anyway I would replace the WP and cap and rotor as mentioned if the opti is otherwise in good shape, (optical sensor portion not corroded, no play in the drive shaft....they can and do wear out) the WP's on seem to go bad between 60-90K in my experience with the LT1. Also, consider upgrading to an electric WP, and gain ~10HP with better cooling.
. I do think upgrading to the manual version's 3.45 gears would make it much more lively, and you have to get it tuned anyway I would replace the WP and cap and rotor as mentioned if the opti is otherwise in good shape, (optical sensor portion not corroded, no play in the drive shaft....they can and do wear out) the WP's on seem to go bad between 60-90K in my experience with the LT1. Also, consider upgrading to an electric WP, and gain ~10HP with better cooling. The electric pumps provide "better cooling" at idle when the engine is making no heat.
Even on f-bodies the quick bolton cars use 3200+stall with a stock cam.
When my car was a 20,000mile a year daily driver I had 2800stall 9.5" converter.
That setup drove well enough that at low throttle passengers mistook it for stock, even other gearheads.
A 2500stall 12" converter is going to run hotter than a 3200stal quality 9.5" unit, price and ignorance are the only excuses for using one.
People come to forums looking for blind support of their ignorant decisions, I tend to disappoint them on that.
My car was at one time a 20,000mile a year daily driver with a ZZ4 cam 3.42s and 2800stall and before that I did stupid stuff like cam with stock gears, crappy 2600stall converter.
Even on f-bodies the quick bolton cars use 3200+stall with a stock cam.
When my car was a 20,000mile a year daily driver I had 2800stall 9.5" converter.
That setup drove well enough that at low throttle passengers mistook it for stock, even other gearheads.
A 2500stall 12" converter is going to run hotter than a 3200stal quality 9.5" unit, price and ignorance are the only excuses for using one.
People come to forums looking for blind support of their ignorant decisions, I tend to disappoint them on that.
My car was at one time a 20,000mile a year daily driver with a ZZ4 cam 3.42s and 2800stall and before that I did stupid stuff like cam with stock gears, crappy 2600stall converter.
Thread Starter
Staging Lane
Joined: Dec 2013
Posts: 55
Likes: 0
The electric pumps provide "better cooling" at idle when the engine is making no heat.
Even on f-bodies the quick bolton cars use 3200+stall with a stock cam.
When my car was a 20,000mile a year daily driver I had 2800stall 9.5" converter.
That setup drove well enough that at low throttle passengers mistook it for stock, even other gearheads.
A 2500stall 12" converter is going to run hotter than a 3200stal quality 9.5" unit, price and ignorance are the only excuses for using one.
People come to forums looking for blind support of their ignorant decisions, I tend to disappoint them on that.
My car was at one time a 20,000mile a year daily driver with a ZZ4 cam 3.42s and 2800stall and before that I did stupid stuff like cam with stock gears, crappy 2600stall converter.
Even on f-bodies the quick bolton cars use 3200+stall with a stock cam.
When my car was a 20,000mile a year daily driver I had 2800stall 9.5" converter.
That setup drove well enough that at low throttle passengers mistook it for stock, even other gearheads.
A 2500stall 12" converter is going to run hotter than a 3200stal quality 9.5" unit, price and ignorance are the only excuses for using one.
People come to forums looking for blind support of their ignorant decisions, I tend to disappoint them on that.
My car was at one time a 20,000mile a year daily driver with a ZZ4 cam 3.42s and 2800stall and before that I did stupid stuff like cam with stock gears, crappy 2600stall converter.
Last edited by Wheel Stander; Mar 1, 2014 at 07:06 PM.
The electric pumps provide "better cooling" at idle when the engine is making no heat.
Even on f-bodies the quick bolton cars use 3200+stall with a stock cam.
When my car was a 20,000mile a year daily driver I had 2800stall 9.5" converter.
That setup drove well enough that at low throttle passengers mistook it for stock, even other gearheads.
A 2500stall 12" converter is going to run hotter than a 3200stal quality 9.5" unit, price and ignorance are the only excuses for using one.
People come to forums looking for blind support of their ignorant decisions, I tend to disappoint them on that.
My car was at one time a 20,000mile a year daily driver with a ZZ4 cam 3.42s and 2800stall and before that I did stupid stuff like cam with stock gears, crappy 2600stall converter.
Even on f-bodies the quick bolton cars use 3200+stall with a stock cam.
When my car was a 20,000mile a year daily driver I had 2800stall 9.5" converter.
That setup drove well enough that at low throttle passengers mistook it for stock, even other gearheads.
A 2500stall 12" converter is going to run hotter than a 3200stal quality 9.5" unit, price and ignorance are the only excuses for using one.
People come to forums looking for blind support of their ignorant decisions, I tend to disappoint them on that.
My car was at one time a 20,000mile a year daily driver with a ZZ4 cam 3.42s and 2800stall and before that I did stupid stuff like cam with stock gears, crappy 2600stall converter.
No doubt it would be quicker with a bigger stall, however, most Corvette's see mainly street or road course duty where big stall converter is not as important or needed/wanted; how many LT1 corvette's do you see with a drag specific setup? Not nearly as many as f-bodys or b-bodys for that matter. Every last tenth in the quarter may not matter in this type setup; that's up to the OP.
Thread Starter
Staging Lane
Joined: Dec 2013
Posts: 55
Likes: 0
No doubt it would be quicker with a bigger stall, however, most Corvette's see mainly street or road course duty where big stall converter is not as important or needed/wanted; how many LT1 corvette's do you see with a drag specific setup? Not nearly as many as f-bodys or b-bodys for that matter. Every last tenth in the quarter may not matter in this type setup; that's up to the OP.
A 2800-3200stall quality 9.5" unit is not a dragrace setup. I didn't tell him to go 3800-4000.
A 9.5" unit is substantially lighter making it easier for the engine to react wouldn't that be good for road course?
Far as my ignorance of people skills, people who like to learn appreciate a little bluntness and you have no idea how many people I have at first offended that then thank me. It is harder to communicate over the internet than face to face, easier to lead someone to realize they are wrong bit by bit in a live conversation. Over the internet where we might be hours between replies it just needs to be said when people are wrong.
If you dig around through Ed's old posts you can find him admitting he wont always correct a customer. Telling someone they are wrong creates bad word of mouth, even if the mouth saying it is ignorant.
A 9.5" unit is substantially lighter making it easier for the engine to react wouldn't that be good for road course?
Far as my ignorance of people skills, people who like to learn appreciate a little bluntness and you have no idea how many people I have at first offended that then thank me. It is harder to communicate over the internet than face to face, easier to lead someone to realize they are wrong bit by bit in a live conversation. Over the internet where we might be hours between replies it just needs to be said when people are wrong.
If you dig around through Ed's old posts you can find him admitting he wont always correct a customer. Telling someone they are wrong creates bad word of mouth, even if the mouth saying it is ignorant.
Launching!
Joined: Apr 2013
Posts: 225
Likes: 0
I agree that it is up to the driver of the car to decide what is or is not "drag only".
I have a 93 Corvette. Working on a 5.3L swap (I expect mr. land yacht to make a comment on this)
My car has a ZF6 (ZF S6-40) I am not a fan of automatics.
I have had my car weighed with me in it it was ~3300lbs...so with out me in it, it should be around ~3000lbs.
The most ignorant posts I have seen on all car forums is that a 4.8L with no changes will be a slug in a car that weighs ~1/2 of what the truck it was pulled from weighs.
I have a 93 Corvette. Working on a 5.3L swap (I expect mr. land yacht to make a comment on this)
My car has a ZF6 (ZF S6-40) I am not a fan of automatics.
I have had my car weighed with me in it it was ~3300lbs...so with out me in it, it should be around ~3000lbs.
The most ignorant posts I have seen on all car forums is that a 4.8L with no changes will be a slug in a car that weighs ~1/2 of what the truck it was pulled from weighs.