Hey guys,
Im in the process of getting my motor built and im having some issues with TB size.
I tried searching and there doesnt seem to be alot of ALL MOTOR discussions about ideal TB size or decent TB that fit out cars even with modification.
Keep in mind I am not starting this discussion as a member who is going all-motor because im in the process of saving up for a turbo kit, I want to go all motor because I like custom parts and I want to see what I can pull out of an all motor eco.
The basics of my build are:
- removed balancing shafts
- 11:1 wiseco pistons
- eagle rods
- p&p head
- 1mm over valves
- complete ferria valve train
- comp stage 3 N/A grind cam
- electromotive tec3r stand alone
I plan on turning 8000- 9000 rpms.
I also own a Miller Tig welder so I will be doing alot of custom manifolding on the car. I will be building and designing my own header and intake manifold.
Now on to the throttle body.
I have noticed when alot of people upgrade thier TB they are really maxed out at around 62mm, With a bored out throttle body. A few people around here have used LS1 TB's on thier cars. I think these would be a little too big for an all motor set up. The smallest LS1 tb I have seen in 75mm. Now I have 2 questions:
1) I know the TPS and the IAC on the LS1 are plug and play on the 2.4 harness.... My guess is it would be the same for the eco.... is this true?
2) Is there a smaller LS1 or firebird/camaro TB that would be compatable with our cars? Maybe around 70mm or 68mm ?
I would think that an older V6 firebird would have the same basic harness as the LS1 powered cars (so the same possibility of the sensors being plug and play on a J-car) so they should be compatable?
Now I realize that with the Tec3r I probably dont have to be too concerned about the compatibility, I can calibrate alot of the sensor readings to work with the Tec3r BUT Gm sensors work the best so I need to stay in the "family " so to speak.
Now a few points about size....
Anytime someone asks these questions on here someone says "62mm is fine, so and so has run 13.xx on his set up"
Fact of the matter is, im not trying to copy someones set up, I want to see how much power I can make through experimenting with manifolding, plenum size and tb combinations.
Now the reason I think that there is some room for a bigger tb is this:
I would just look to the honda guys. They have been doing all-motor for way longer than us and they have alot of sucess at it.
Lots of the 1.8l type-r guys are using 64mm to 68mm TB on thier all motor cars and having sucess.
Lots of the H22 and 2l guys are using 64mm to 70mm tb on thier cars as well.
If im going to be turning the same rpms AND having more displacement 62mm is not enough. In my opinion.
So this is my issue:
I can pick up these tb easily:
rsm 62mm
sms 62mm
ebay 60-62mm
BIG GAP
LS1 72mm
LS1 75mm
I need something in between..... any ideas from the GM camp?
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I was about to say that I really didn't think you'd need a throttle body bigger than 62mm, until I went and did some metric conversions. You see, I was thinking along the lines of exhaust, where the smallest part of your exhaust is the bottleneck to the flow, and I applied that idea to the intake side (which may or may not really be a good way of looking at it, I'm not sure). I figured that 62mm would be plenty big as it would probably be a larger diameter than your intake pipe. However, 62mm = 2.44 inches, and most intakes are 2.75" IIRC. So, just going by that rationale, 72mm = 2.83 inches. That really may not be too big honestly, especially with all the other mods to back it up that you're describing (bigger cams, oversized valves, higher compression, custom intake manifold). I'd say if you can't find a simple option in the range you're looking for, just give the 72mm a try. Considering the RPM range you're planning on running to, I don't think it sounds like too big of a deal to you that you might lose a little power down low.
i think the smallest version of the LS style tb is 70 mm from the V6 trucks
karo's motor made about 250whp n/a with a 75mm tb , with a old computer and not really tunable , since hpt wasnt heard of for us at the time , i wonder how much more power coulda been drawn out of his motor now
SMG is probably what he's thinking.
I did the math a long time ago, and 65mm is about ideal if you're seeing 100% volumetric efficency, which you're not. So a 62mm will be just fine
Built, bottled, ready for 11s. 14.446@93.74mph, 1.848 60' N/A.
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I'd say if you can't find a simple option in the range you're looking for, just give the 72mm a try. Considering the RPM range you're planning on running to, I don't think it sounds like too big of a deal to you that you might lose a little power down low.
I think that a bigger tb would produce more power up high, this is fine, the cam grind I chose is all up high. According to COMP they're not supposed to make much power until 4000-5000 rpms.
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i think the smallest version of the LS style tb is 70 mm from the V6 trucks
karo's motor made about 250whp n/a with a 75mm tb , with a old computer and not really tunable , since hpt wasnt heard of for us at the time , i wonder how much more power coulda been drawn out of his motor now
Im going to have to go to a yard and take a look for a 70mm tb. As well, I had no idea Karo was making all that power with a 75mm tb, he is just another example that 62mm is too small.
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sms is not 69mm. its factory outlet by the rear. I did a post about it.
I have no idea where I said sms was 69mm in my post, If it was 69mm i'd buy it. If I typed that .... my mistake!
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I did the math a long time ago, and 65mm is about ideal if you're seeing 100% volumetric efficency, which you're not. So a 62mm will be just fine
Ive done the math too, and yes, with propper manifolding using resonance wave tuning you can achive 100% VE, but besides that, between KARO and a bunch of guys on Honda-tech, Im going to try a big tb on a dyno and then decide for myself.
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with propper manifolding using resonance wave tuning you can achive 100% VE,
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at about 3000 rpm the Quad-4's volumetric efficiency is more than 1-about 1.05- because of tuning
-Setting the Pace- Oldsmobile's first 100 years by H.J. Early and J.R. Walkinshaw
it seems that the original quad 4's intake manifold might be a good choice, would the mani have that efficiency benefit at, say, 6000 and 9000 rpm also?
LD9 F23 FTW!!
^^^^oops, sorry, I was thinking LD9, not eco...
LD9 F23 FTW!!
Hey Game Over Racing, Im looking at building a crazy NA motor too man! Good luck. And i have an even better answer for your Throttle body question. The TEC3 has been used on many cars including Mustangs. They have a TPS sensor that you can buy for like $80. There is wiring to do, but it is simple, and that is a complete stand alone, so no matter what wiring is required anyways. Now for a 70mm Throttle body I would give Accufab a call about there 70mm throttle body. If you want to go cheaper call BBK. These are awesome throttle bodies and give great power gains. And if you want to go where Ron Lummus went, you can also get a 100mm throttle body!! Thats way of an overkill, but you could have the most interesting ecotec!! lol
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Now for a 70mm Throttle body I would give Accufab a call about there 70mm throttle body. If you want to go cheaper call BBK. These are awesome throttle bodies and give great power gains.
Thanks for the advice, I was thinking of looking into some Mustang parts as well. Im probably going to try out a 70mm (from a mustang) and a 75mm from a Trans am and see which one gives the best power gain.
I already bought the Tec3r so Yeah, Im going to be doing wiring anyway so it shouldnr be a big deal
Thanks for the recomendation.
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Gameoverracing. wrote:
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I did the math a long time ago, and 65mm is about ideal if you're seeing 100% volumetric efficency, which you're not. So a 62mm will be just fine
Ive done the math too, and...
Could anyone who has claimed to have "done the math" please show us the math???
I, for one, would love to see the formulas and values you used to draw conclusions from.
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Could anyone who has claimed to have "done the math" please show us the math???
I, for one, would love to see the formulas and values you used to draw conclusions from.
You may want to check with Owen on that one as far as the math for TB size, I was refering to the math used to achieve over 100% VE using manifold and header design.
The math for TB size must be some sort of a proportion between VE vs. Displacement vs. TB size, but I dont really know the calculations for that. However I do know all the propper calculations for header design and intake manifold design to impove VE.
As far as TB size, why did you choose to put a 75mm tb on Karo's car? You were the one who built it wern't you? Why dont you give us some insight on that.
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If you are going all out, just get a 90mm Nick williams TB or a FAST 90 TB for the LS cars?
2004 Cavalier. Razzi. (Sold)
1998 Corvette. Some mods.
1992 Typhoon. Lots of mods.
1994 Civic VX 44MPG
if you wanted a midsized easy to work with TB, instead of getting one of a 2.8 firebird....go for a fiero, they are at least round instead of oval (unless oval floats your boat.), also I believe the company west coast fiero has ported versions of that, which would give you a better mid-range port size.
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If you are going all out, just get a 90mm Nick williams TB or a FAST 90 TB for the LS cars?
Im not so sure I need a TB that big, im going to start at around 70mm and go up from there... good suggestion though.
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if you wanted a midsized easy to work with TB, instead of getting one of a 2.8 firebird....go for a fiero, they are at least round instead of oval (unless oval floats your boat.), also I believe the company west coast fiero has ported versions of that, which would give you a better mid-range port size.
Do you know the size of the fiero tb? is it close to 70mm?
ill probably go to a wrecking yard soon and see whats available.....
"Go Before Show Yo."
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Gameoverracing. wrote:Quote:
If you are going all out, just get a 90mm Nick williams TB or a FAST 90 TB for the LS cars?
Im not so sure I need a TB that big, im going to start at around 70mm and go up from there... good suggestion though.
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if you wanted a midsized easy to work with TB, instead of getting one of a 2.8 firebird....go for a fiero, they are at least round instead of oval (unless oval floats your boat.), also I believe the company west coast fiero has ported versions of that, which would give you a better mid-range port size.
Do you know the size of the fiero tb? is it close to 70mm?
ill probably go to a wrecking yard soon and see whats available.....
I sent an email to west coast fiero to get the exact specs on the TB's off of the 2.8's. ill post up when i hear back from them.
Gameoverracing. wrote:
As far as TB size, why did you choose to put a 75mm tb on Karo's car? You were the one who built it wern't you? Why dont you give us some insight on that.
The overwhelmingly simple answer was cost.
It was only $35 to buy and put on the 75 on vs. who knows how much to get a custom made (and correctly made) larger than 62mm.
As far as choosing a size, I did no math. I just compared the size of many factory engines making about the same HP as we targetted and added a small fudge factor to end up at least large enough. 75mm was bigger than the target but way cheap.
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I just compared the size of many factory engines making about the same HP as we targetted and added a small fudge factor to end up at least large enough. 75mm was bigger than the target but way cheap.
If you dont mind me asking, what did you come up with as ideal? I was thinking around 70mm, what do you think?
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do you guys have a pic of the stock 2.4 TB?
IF it'll fit, the 60degreev6 store sells a very nice 65mm TB. I'm making just under 300 N/A HP on one.. (altho in a V6).
Pic:
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IF it'll fit, the 60degreev6 store sells a very nice 65mm TB. I'm making just under 300 N/A HP on one.. (altho in a V6).
Thanks for the recommendation. As far as fitting, I plan on welding up my own intake mani, so Ill be getting a flange made. So in short.... I can make anything fit!
Ill have to look into the sensors and see if they are similar, .... since ill be using a tec3 i think ill be fine. So i guess with this thread we've filled in alot of the blanks on tb size. We have a 62mm, 65mm, 70mm, and 75mm.
thats alot of options......
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