Realistic hp gains
Thread Starter
Instructor
Joined: Dec 2012
Posts: 120
Likes: 1
From: Canton Georgia
Realistic hp gains
Hey guys im in the middle of an engine swap in my 86 and im wondering how much power i might gain from this stuff. So basically i started with a stock 86 so 230hp and 230 tq i guess. Im putting an 87 motor in that has the aluminum heads. So right of that bat i gain 10 hp and 15 tq.
Now im putting obx headers on the new engine along with throwing out the old cats and running flow master mufflers. I have a k&n air filter 180 thermo and im going to get it tuned at pcm for less. The car will have pretty much new everything fuel injectors egr all the basic stuff it needs to run good. Should i get a hotter coil for it and gap the plugs more? Or is that a waste of time? Its got 3.07 rear gears on it. Besides what i said above im not willing to change the heads or intake or came right now. I really just want to drive it
But while im here i might as well do these little things. What do you guys think my gains will be like?
Now im putting obx headers on the new engine along with throwing out the old cats and running flow master mufflers. I have a k&n air filter 180 thermo and im going to get it tuned at pcm for less. The car will have pretty much new everything fuel injectors egr all the basic stuff it needs to run good. Should i get a hotter coil for it and gap the plugs more? Or is that a waste of time? Its got 3.07 rear gears on it. Besides what i said above im not willing to change the heads or intake or came right now. I really just want to drive it
But while im here i might as well do these little things. What do you guys think my gains will be like?
Last edited by sansonic; Feb 3, 2014 at 02:36 PM.
Team Owner
Joined: Dec 2000
Posts: 21,094
Likes: 282
From: Phila., PA burbs
Your old engine stock was probably putting down 200 or so HP at the rear wheels. With the minor mods you've mentioned I'm guessing you'd be up to 225 HP at the wheels give or take. If you want a more realistic number you'd have to dyno before/after or take it to the track before/after. Either way, you're not looking at a significant increase without more mods (intake, heads, cam). 
Melting Slicks
Joined: Jun 2013
Posts: 3,065
Likes: 39
Hey guys im in the middle of an engine swap in my 86 and im wondering how much power i might gain from this stuff. So basically i started with a stock 86 so 230hp and 230 tq i guess. Im putting an 87 motor in that has the aluminum heads. So right of that bat i gain 10 hp and 15 tq.
Now im putting obx headers on the new engine along with throwing out the old cats and running flow master mufflers. I have a k&n air filter 180 thermo and im going to get it tuned at pcm for less. The car will have pretty much new everything fuel injectors egr all the basic stuff it needs to run good. Should i get a hotter coil for it and gap the plugs more? Or is that a waste of time? Its got 3.07 rear gears on it. Besides what i said above im not willing to change the heads or intake or came right now. I really just want to drive it
But while im here i might as well do these little things. What do you guys think my gains will be like?
Now im putting obx headers on the new engine along with throwing out the old cats and running flow master mufflers. I have a k&n air filter 180 thermo and im going to get it tuned at pcm for less. The car will have pretty much new everything fuel injectors egr all the basic stuff it needs to run good. Should i get a hotter coil for it and gap the plugs more? Or is that a waste of time? Its got 3.07 rear gears on it. Besides what i said above im not willing to change the heads or intake or came right now. I really just want to drive it
But while im here i might as well do these little things. What do you guys think my gains will be like?
Thread Starter
Instructor
Joined: Dec 2012
Posts: 120
Likes: 1
From: Canton Georgia
Your old engine stock was probably putting down 200 or so HP at the rear wheels. With the minor mods you've mentioned I'm guessing you'd be up to 225 HP at the wheels give or take. If you want a more realistic number you'd have to dyno before/after or take it to the track before/after. Either way, you're not looking at a significant increase without more mods (intake, heads, cam).
Le Mans Master
Joined: Mar 2004
Posts: 5,107
Likes: 171
From: Dublin CA
The HP of 230 for the 86 is measured at the engine not the rear wheels.
The 87 was stock with 240 HP at the engine and 343 pounds of torque. You will probably pick up 10-15 HP with the headers. Filter and thermostat will give you nothing. Tune might pick up a couple of HP but not much. Hotter coil will give you nothing...same with the gap on the plugs. The HEI should be able to jump a gap to about .45 if you really want, but will not yield anything to make the engine run better or add HP. I would keep the gap at .35.
You would pick up some HP with new heads and really make things happen with heads, cam and intake. Add 1.6 roller rockers to the stock engine and pick up another 3-5 HP.
All your changes on the conservative side will give you about 250 at the crank or about 210 at the rear wheels. You loose about 15-20% from the crank to the rear end.
The 87 was stock with 240 HP at the engine and 343 pounds of torque. You will probably pick up 10-15 HP with the headers. Filter and thermostat will give you nothing. Tune might pick up a couple of HP but not much. Hotter coil will give you nothing...same with the gap on the plugs. The HEI should be able to jump a gap to about .45 if you really want, but will not yield anything to make the engine run better or add HP. I would keep the gap at .35.
You would pick up some HP with new heads and really make things happen with heads, cam and intake. Add 1.6 roller rockers to the stock engine and pick up another 3-5 HP.
All your changes on the conservative side will give you about 250 at the crank or about 210 at the rear wheels. You loose about 15-20% from the crank to the rear end.
Thread Starter
Instructor
Joined: Dec 2012
Posts: 120
Likes: 1
From: Canton Georgia
The HP of 230 for the 86 is measured at the engine not the rear wheels.
The 87 was stock with 240 HP at the engine and 343 pounds of torque. You will probably pick up 10-15 HP with the headers. Filter and thermostat will give you nothing. Tune might pick up a couple of HP but not much. Hotter coil will give you nothing...same with the gap on the plugs. The HEI should be able to jump a gap to about .45 if you really want, but will not yield anything to make the engine run better or add HP. I would keep the gap at .35.
You would pick up some HP with new heads and really make things happen with heads, cam and intake. Add 1.6 roller rockers to the stock engine and pick up another 3-5 HP.
All your changes on the conservative side will give you about 250 at the crank or about 210 at the rear wheels. You loose about 15-20% from the crank to the rear end.
The 87 was stock with 240 HP at the engine and 343 pounds of torque. You will probably pick up 10-15 HP with the headers. Filter and thermostat will give you nothing. Tune might pick up a couple of HP but not much. Hotter coil will give you nothing...same with the gap on the plugs. The HEI should be able to jump a gap to about .45 if you really want, but will not yield anything to make the engine run better or add HP. I would keep the gap at .35.
You would pick up some HP with new heads and really make things happen with heads, cam and intake. Add 1.6 roller rockers to the stock engine and pick up another 3-5 HP.
All your changes on the conservative side will give you about 250 at the crank or about 210 at the rear wheels. You loose about 15-20% from the crank to the rear end.
Drifting
Joined: May 2006
Posts: 1,428
Likes: 7
From: Chewelah Wa
The HP of 230 for the 86 is measured at the engine not the rear wheels.
The 87 was stock with 240 HP at the engine and 343 pounds of torque. You will probably pick up 10-15 HP with the headers. Filter and thermostat will give you nothing. Tune might pick up a couple of HP but not much. Hotter coil will give you nothing...same with the gap on the plugs. The HEI should be able to jump a gap to about .45 if you really want, but will not yield anything to make the engine run better or add HP. I would keep the gap at .35.
You would pick up some HP with new heads and really make things happen with heads, cam and intake. Add 1.6 roller rockers to the stock engine and pick up another 3-5 HP.
All your changes on the conservative side will give you about 250 at the crank or about 210 at the rear wheels. You loose about 15-20% from the crank to the rear end.
The 87 was stock with 240 HP at the engine and 343 pounds of torque. You will probably pick up 10-15 HP with the headers. Filter and thermostat will give you nothing. Tune might pick up a couple of HP but not much. Hotter coil will give you nothing...same with the gap on the plugs. The HEI should be able to jump a gap to about .45 if you really want, but will not yield anything to make the engine run better or add HP. I would keep the gap at .35.
You would pick up some HP with new heads and really make things happen with heads, cam and intake. Add 1.6 roller rockers to the stock engine and pick up another 3-5 HP.
All your changes on the conservative side will give you about 250 at the crank or about 210 at the rear wheels. You loose about 15-20% from the crank to the rear end.
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Thread Starter
Instructor
Joined: Dec 2012
Posts: 120
Likes: 1
From: Canton Georgia
Thanks for all the input one last question. Do you think i will be able to feel the difference? Like will the car feel like its been woken up? Right now im stuck driving a little saturn with about 100hp and 100tq so i know it will feel waay faster than that. Im just really exicted to be driving my vette again i cant wait.
Le Mans Master
Joined: Mar 2004
Posts: 5,107
Likes: 171
From: Dublin CA
Add the headers and the roller rockers and there will be a seat of the pants difference. When I first started to mod the 85, one of the first things I did was add 1.5 & 1.6 RR's. You could feel the difference. This won't be throw you back against the seat....but you will notice.
Team Owner
Joined: Sep 2001
Posts: 62,153
Likes: 1,731
From: Athens AL
C7 of the Year - Unmodified Finalist 2021
C4 of Year Finalist (performance mods) 2019
Thanks for all the input one last question. Do you think i will be able to feel the difference? Like will the car feel like its been woken up? Right now im stuck driving a little saturn with about 100hp and 100tq so i know it will feel waay faster than that. Im just really exicted to be driving my vette again i cant wait.
Race Director
Joined: Apr 2003
Posts: 17,700
Likes: 1,667
From: moraga ca
It's amazing when you start throwing money and parts at one of these cars, the car feels much faster even though it may or may not be. After every change, you will get an "aww, that's faster" feeling.
Thread Starter
Instructor
Joined: Dec 2012
Posts: 120
Likes: 1
From: Canton Georgia
Would there be any power gains to putting an adjustable fuel pressure regulator? I actually have an upgraded fuel pump in the car (got a good deal on it) its a walbro 255l/hr fuel pump i think the part number is gss204m. I know its a overkill for this car but if adding a little fuel pressure could help with the headers and the tune id be down for it.
Le Mans Master
Joined: Mar 2004
Posts: 5,107
Likes: 171
From: Dublin CA
No noticeable gains with a adjustable fuel pressure regulator. Stock fuel pump is good for up to about 400 HP and your a LONG way from there.
Go to the above post by Vader86 and click on his name...then down to his home page and visit. He has a listing of things that help and those that do not.
Cut out the cover over the air filter. You can play with the distributor base setting to see what your car likes. Standard is 6 degrees, but my 85 liked 10 better. You can also adjust the TPS to .60 and will give you a little more quick pickup. Cut back the spark plugs and that will add a whole 1/4 HP...but they all add up. Take the money you would have spent on the fuel pump and buy the March 3 piece underdrive pulleys.
If you get adventurous and are willing to try this yourself, gasket match the runners to the intake, match the runners to the plenum and port the plenum. Easy to do with a die grinder.
Go to the above post by Vader86 and click on his name...then down to his home page and visit. He has a listing of things that help and those that do not.
Cut out the cover over the air filter. You can play with the distributor base setting to see what your car likes. Standard is 6 degrees, but my 85 liked 10 better. You can also adjust the TPS to .60 and will give you a little more quick pickup. Cut back the spark plugs and that will add a whole 1/4 HP...but they all add up. Take the money you would have spent on the fuel pump and buy the March 3 piece underdrive pulleys.
If you get adventurous and are willing to try this yourself, gasket match the runners to the intake, match the runners to the plenum and port the plenum. Easy to do with a die grinder.
Team Owner
Joined: Sep 2001
Posts: 62,153
Likes: 1,731
From: Athens AL
C7 of the Year - Unmodified Finalist 2021
C4 of Year Finalist (performance mods) 2019
Would there be any power gains to putting an adjustable fuel pressure regulator? I actually have an upgraded fuel pump in the car (got a good deal on it) its a walbro 255l/hr fuel pump i think the part number is gss204m. I know its a overkill for this car but if adding a little fuel pressure could help with the headers and the tune id be down for it.
The Walbro is what I have, its more than plenty for you.
Thread Starter
Instructor
Joined: Dec 2012
Posts: 120
Likes: 1
From: Canton Georgia
No noticeable gains with a adjustable fuel pressure regulator. Stock fuel pump is good for up to about 400 HP and your a LONG way from there.
Go to the above post by Vader86 and click on his name...then down to his home page and visit. He has a listing of things that help and those that do not.
Cut out the cover over the air filter. You can play with the distributor base setting to see what your car likes. Standard is 6 degrees, but my 85 liked 10 better. You can also adjust the TPS to .60 and will give you a little more quick pickup. Cut back the spark plugs and that will add a whole 1/4 HP...but they all add up. Take the money you would have spent on the fuel pump and buy the March 3 piece underdrive pulleys.
If you get adventurous and are willing to try this yourself, gasket match the runners to the intake, match the runners to the plenum and port the plenum. Easy to do with a die grinder.
Go to the above post by Vader86 and click on his name...then down to his home page and visit. He has a listing of things that help and those that do not.
Cut out the cover over the air filter. You can play with the distributor base setting to see what your car likes. Standard is 6 degrees, but my 85 liked 10 better. You can also adjust the TPS to .60 and will give you a little more quick pickup. Cut back the spark plugs and that will add a whole 1/4 HP...but they all add up. Take the money you would have spent on the fuel pump and buy the March 3 piece underdrive pulleys.
If you get adventurous and are willing to try this yourself, gasket match the runners to the intake, match the runners to the plenum and port the plenum. Easy to do with a die grinder.
Le Mans Master
Joined: Mar 2004
Posts: 5,107
Likes: 171
From: Dublin CA
Reduces the parasitic drain from the accessories by reducing the pulley size. The pulley for the alternator is a little larger so the alternator is still able to put out the amps at idle.
This allows the engine to spin up a little faster into your HP/Torque range.
From Vader86's site..... "Personally I dont like this mod, because I dont like the idea of my Alternator spinning any slower than it already does, especially since the C4 eats alternators. However, track tests show that you could get .1 in the 1/4mi just from this, which equates to about 10hp."
This allows the engine to spin up a little faster into your HP/Torque range.
From Vader86's site..... "Personally I dont like this mod, because I dont like the idea of my Alternator spinning any slower than it already does, especially since the C4 eats alternators. However, track tests show that you could get .1 in the 1/4mi just from this, which equates to about 10hp."
Team Owner
Joined: Sep 2003
Posts: 20,179
Likes: 673
From: Freedom is never more than one generation away from extinction.
St. Jude '03 thru '24
Look.
If your looking for extra power put a cam in that motor!
The cost is not prohibitive like heads abut you'll add 40-50 smiles per mile easy.
Then pickup the heads later on.
All that other junk your looking at is worthless... in comparison
If your looking for extra power put a cam in that motor!
The cost is not prohibitive like heads abut you'll add 40-50 smiles per mile easy.
Then pickup the heads later on.
All that other junk your looking at is worthless... in comparison
