Bigger throttle bodies?

[Sybil TF]

With all my upgrades I'm about as far as I can go with easy bolt ons. Are the bigger throttle bodies a waste of money?

[The Stig]

13110

[99RT10]

Some say if you have the supporting mods, you might get another 10 HP

[Sybil TF]

Some say if you have the supporting mods, you might get another 10 HPIs that with porting the intake to match or just bolting them on?

[99RT10]

I think most just open the front a touch so there is no impedance to flow and go.

[Sybil TF]

I think most just open the front a touch so there is no impedance to flow and go. Thanks!

[dave6666]

At your hp level they are a waste. You might even lose power due to the reduced velocity through them.

[Sybil TF]

At your hp level they are a waste. You might even lose power due to the reduced velocity through them.I see them used here and there. If they are cheap enough i may try them and see. Is the throttle position sensor fixed or is it adjustable on these cars?

[dave6666]

I see them used here and there. If they are cheap enough i may try them and see. Is the throttle position sensor fixed or is it adjustable on these cars?

Brilliant. Do the EXACT OPPOSITE of the advice you are being given here. IGNORE the fact that the cars "here and there" that you see them on are well in excess of your near stock power level. And putting them on your car can actually hurt your performance.

Brilliant.

And do what? Is the throttle position sensor adjustable? Do you know anything technical about these cars? I mean anything? How about, like how many volts DC the ECM system uses outboard of the module itself? Because if you are scaling to the non adjustable TPS sensor you'll need to know that.

You are scaling to your sensor right?


Huh? Do what? The 70mm TB's are shiny and look kuul? Oh, then by all means, get them lmao.

[Sybil TF]

Brilliant. Do the EXACT OPPOSITE of the advice you are being given here. Thanks for the compliment. And yes I agree it is brilliant to gather info and the advice from 99RT 10 says 10 hp so if pick up some used ones cheap for my dyno run the car can be ran with both and determine which one of you is correct.

And since you have been wrong before I will find out for myself...:drive:

[stuntman]

Well, the benefit of larger TB's has been a bunch of hearsay. No one has posted the results of a back to back swap (swapping them on the dyno), so I say go for it and post the results!

What are you making now?

[99RT10]

Thanks for the compliment. And yes I agree it is brilliant to gather info and the advice from 99RT 10 says 10 hp so if pick up some used ones cheap for my dyno run the car can be ran with both and determine which one of you is correct.

And since you have been wrong before I will find out for myself...:drive:

Remember I said "maybe" :D

If you get them, do a couple of Dyno pulls to get a good baseline, then swap them out and do 2 more pulls. Take it to 5900-6000. If they pick up HP, it will be on the high end of the RPM spectrum.

[slovenom]

Brilliant. Do the EXACT OPPOSITE of the advice you are being given here. IGNORE the fact that the cars "here and there" that you see them on are well in excess of your near stock power level. And putting them on your car can actually hurt your performance.

Brilliant.

And do what? Is the throttle position sensor adjustable? Do you know anything technical about these cars? I mean anything? How about, like how many volts DC the ECM system uses outboard of the module itself? Because if you are scaling to the non adjustable TPS sensor you'll need to know that.

You are scaling to your sensor right?


Huh? Do what? The 70mm TB's are shiny and look kuul? Oh, then by all means, get them lmao.

Dave ftw!!

[Luisv]

..... Or you can ask an engine builder to run the setup on a virtual Dyno to see if there is a true gain. I did similar with a Chevy 350 that we are building for a 77 Vette. I had my engine builder create a setup that used off the shelf components. He plugged in the data (flow figures, cam specs, exhaust size and configuration, trans gearing, differential, rear tire size, etc, etc) and he can give me relative gains in power, torque & even 1/4 mile times. For that car we ended up at a 383 stroker that will produce about 480HP and about 400 ft-lbs of torque at about 2000 RPM peaking at about 440 ft-lbs.

Most builders that have this ability/service/software charge to do it, but it may be cheaper than buying parts that may or may not work. I'd be happy to give you my builders name/e-mail and you can chat with him.

One note on this and my opinion. I am sure that others will chime in and agree. (as I am certain one will call me an idiot simply because.... well.... who the hell knows) What makes these car exciting is not the top HP number. It's the torque and the torque curve. Sure that HP will dictate top speed and it's nice to talk HP, but the torque and how and when it is available is what makes the V10 awesome. I would look at that when considering whether or not to do the mod.

As for whether it will help or not.... the engine is an air pump. The more air, the more fuel. Squeeze that down and ignite. If you can increase the air/fuel going into the car, the better the power you will make. The mods I see on your engine are the 1.7 RR's and the exhaust. In both cases you are improving the air flow. If you put the larger throttle bodies then you will get more flow into the intake manifold. I you have a stock Gen2 manifold, then you should port the intakes to match the bodies. Once you have it off, I would consider having the ports on the head side matched to the heads. As for flow velocity at the TB's.... I would imagine that it would not make a difference because the Gen 2 intake opens into a larger space to feed the runners. ie. The two large "blocks" on both sides of the intake are basically hollow rectangles. The velocity you should be concerned with is the runner into each cylinder where fuel gets mixed. Bottom line, the larger TB's will give you more air flow and likely more power. How much more.... that's the deal. If your gain is 10HP and 5 ft-lbs of torque.... you won't feel it. Like I mentioned earlier, if that gives you and extra 20 ft-lbs of torque.... you'll definitely feel that.

Good luck... hit me up if you want the info on the tech.

[Sybil TF]

I realize bolting on a part doesn't make magic and create hp. But with my opened up exhaust and other mods getting more air in may help since it is opened up on the back end. Everyone told me don't put 1 7/8th long tube headers on our ram for you will lose torque. Go 1/3/4. I can tell you that the power is very noticeable over the stock when you mash the gas and the mpg went up 2 so experimenting is the way I roll lol.

Seriously tho, I can see losing torque on a stock motor but on mine it may help but if not I'm sure they will if I go sc...

[Luisv]

I realize bolting on a part doesn't make magic and create hp. But with my opened up exhaust and other mods getting more air in may help since it is opened up on the back end. Everyone told me don't put 1 7/8th long tube headers on our ram for you will lose torque. Go 1/3/4. I can tell you that the power is very noticeable over the stock when you mash the gas and the mpg went up 2 so experimenting is the way I roll lol.

Seriously tho, I can see losing torque on a stock motor but on mine it may help but if not I'm sure they will if I go sc...

Exactly the point.... Test and then decide. Reason I suggested a builder run virtual numbers is that you could test the TB's with your current setup AND with potential future upgrades. For example, if you are planning on a supercharger setup at some point, the TB's might be detrimental. You could have a builder run numbers and test future plans.... This way you can choose wisely for now AND the future.

On the Torque comments above.... All I mean... Make sure you gain where you want the gain... ie... How many times will you hit the top speed on the car? Likely not many times if ever. However, if you track the car the added torque at the right RPM will be far more important....

[Sybil TF]

You can feel the small increases with mods like headers, R&R's etc. when you get to know your car well. Most people couldn't tell the difference but I figured someone who has them would have chimed in by now.

[C5Longhorn]

I don't think there will be a gain with current mods. I think at a minimum you would need a good port matched head and cam job before considering TB's. Certainly would be easy to test and see, but not worth the money to me to find out.

Good luck and let us know.

Rick

[ViperTony]

I don't think there will be a gain with current mods. I think at a minimum you would need a good port matched head and cam job before considering TB's. Certainly would be easy to test and see, but not worth the money to me to find out.

Good luck and let us know.

Rick

Agreed. I don't feel any difference with all of my mods on the GenII and the addition of larger TB's. My builder told me at best maybe another 10-15 hp with them on with heads, cam, ported intake, headers, HF cats, exhaust, etc. Never did a before and after with the TB's but I can't notice a difference. They look good though. Very shiny and big.

[Sybil TF]

Agreed. I don't feel any difference with all of my mods on the GenII and the addition of larger TB's. .Are you saying your senses are weak or the mods were a waste of money. Legitimate question and not an insult here but I can tell a difference, especially with the header cat removal mod.

[Camfab]

Based on other similar threads, I've come to realize that some individuals really aren't interested in facts. Just opinions that support their own bias.

[Dan Cragin]

We did quite a bit of testing with bigger throttle bodies on the Gen 2 engine. A minor peak hp gain was seen, but low speed driveability suffered. With a much bigger cam the 67-70mm T-Bodies proved to be worthwhile.

[Sybil TF]

We did quite a bit of testing with bigger throttle bodies on the Gen 2 engine. A minor peak hp gain was seen, but low speed driveability suffered. With a much bigger cam the 67-70mm T-Bodies proved to be worthwhile.Was that a creampuff gen 2 or the 96-99 708 cam? Also did your testing include mods like headers and 1.7 RR's? Thanks for the info!

[Sybil TF]

Based on other similar threads, I've come to realize that some individuals really aren't interested in facts. Just opinions that support their own bias.
LOL, that is true but I have found on these cars no two are the same. For instance, I would be an idiot for removing my cats for it will smell like a rotten egg. So far, no smell whatsoever. Some of the so called "experts" with facts have been wrong on my car. Of course I have a 96 GTS which is the unicorn of the viper so the laws of physics don't apply....:smilielol:

[ViperTony]

Are you saying your senses are weak or the mods were a waste of money. Legitimate question and not an insult here but I can tell a difference, especially with the header cat removal mod.

Didn't write anything about my senses being weak there Champ. This may help. (https://secure.hookedonphonics.com/offers/learn-to-read-scrn-2stp.aspx?vc=EMG1&pc=SEMGCI&gclid=COK6o_XZ_scCFYhbfgod9a0NCw)

I think that larger TB's on an otherwise stock engine is a waste of money. It's also questionable doing larger TB's on a modded engine...it makes sense (See Dan's post) but for a few HP...WHY do it?!? Are you going to feel 20 more horsepower? Is it going to drop your ETs at the strip? I have a Greg Good cam which is a little more aggressive cam than the 708. I seriously cannot tell the difference with or without cats. What I have noticed, odd as it may sound, is that the loud sucking noise :) I used to hear, while standing in front of the naca duct, is subdued. It no longer sounds as if it's breathing was restricted. But I also have ported intake. I did the TB and intake at the same time so who knows what cleared up the 'congestion'.

For reference, I have:

- Creampuff
- GG Ported heads/intake/CAM/Port Matched
- T&D Rockers
- Belanger Headers/catback
- HF cats
- SCT Tune
- Pushrods/Lifters
- Modified stock airbox to accept 3" tubes/TBs

If you find the AccuFab TB's used send them to Accufab and they will set up the blade positioning properly. I've seen used sets missing the set screws, blades not set right, etc. AccuFab didn't charge me anything and they threw in set of TB gaskets that fit. You'll also need to modify your stock airbox housing (back). Roe used to sell this. Otherwise you'll need to do the 3" to 2.5" reducer...which why bother? Or get a JMB airbox configured for the 70mm TBs.

But it's your money do whatever makes you happy.

[tagoo]

My setup is nearly identical to Tony's (I have HS rockers though). I'm not sure I would do the 70mm TBs again except for the fact that they look better than the stock TBs. Low speed, low gear driving is definitely more difficult as a small amount of pressure on the gas pedal opens the TB more. One little press on the gas pedal causes the car to jerk forward, which causes my foot to move which sets off a cycle of increasing jerks until i press in the clutch or stabilize my foot by pressing it against the transmission tunnel. If I keep the side of my foot tight against the trans tunnel, I'm able to drive smoothly in low gear, low speed. I attribute this difficulty to the large TB's. My turner confirmed that his experience was the same. No issues once the TBs are cracked open a bit more.

Regarding "feeling" the difference between small power adders... I'm glad some people can tell the difference because i sure can't. I've spent a lot of time at the drag strip. One day I couldn't figure out why my ET and traps were down. I then found that one of my spark plug wires had popped off the plug. I didn't notice that I was only running on 9 cylinders except for the time slip. If I didn't notice a 50 hp drop (granted, I may be old and numb), I seriously doubt anyone will be able to "feel" a 10 HP change.

[stuntman]

The TBs have their own "cam" to open the throttle, right?

TBs typically don't have round/linear "pulleys"/" cam" (brain farting on the proper term), and the throttles open slower in the first 1/4 of pedal travel. If you volt on a round/linear "cam" to a stock TB, it will also be much touchier and jumpy/overly responsive. I'll have to check my car to see how the stock cam is designed, I don't think it's round.

[Sybil TF]

Didn't write anything about my senses being weak there Champ. This may help. (https://secure.hookedonphonics.com/offers/learn-to-read-scrn-2stp.aspx?vc=EMG1&pc=SEMGCI&gclid=COK6o_XZ_scCFYhbfgod9a0NCw)

.Sorry, I misunderstood. My bad. You can feel the difference with all of your mods, but TB's you can't. So this is good info here. Thanks for the input.

[tagoo]

No offense taken. My point was that for me, it is VERY difficult to tell if I am making more or less power unless I have instrumentation. As an example, I point to the time at the track that one of my spark plug wires popped off and I was only running on 9 cylinders. If not for the timing slip, I don't believe I would have noticed that my power was down between runs. I, therefore, hypothesize that if I cannot tell (without instruments) when I lose 50 HP or so from having a cylinder not fire, then I am skeptical that others can discern a difference of only 10 hp without using instrumentation.

When I added Heads/cam/RR/Headers/etc, it gave me an additional 150 rwhp (instrumentation via before/after dyno). Surprisingly, the additional 150 didn't "feel" that much faster except that i noticed I had to shift gears much more quickly going down the track. The time slips showed that I was much faster too.

After the above mentioned mods, I added 3:55 gears. Interestingly, that mod gave me about the same sensation of increased power/speed as the heads/cam/etc, even though I wasn't going any faster or making any more power.

For me, this suggests that the human body is not a great instrument for determining small or changes acceleration. Or, maybe my senses are super-weak.


Did you say? " I don't feel any difference with all of my mods and the addition of TB's.."
so either
[ ] I have super human senses
[ ] Your senses are weak
[ ] your mods and mine are a total waste of money including TB's. Might as well leave it stock...

By the way I'm not being a smart alec in a hurtful way, don't get offended...:smilielol:

[tagoo]

I think i just answered a question that wasn't asked of me. Oh, well. Sorry.



No offense taken. My point was that for me, it is VERY difficult to tell if I am making more or less power unless I have instrumentation. As an example, I point to the time at the track that one of my spark plug wires popped off and I was only running on 9 cylinders. If not for the timing slip, I don't believe I would have noticed that my power was down between runs. I, therefore, hypothesize that if I cannot tell (without instruments) when I lose 50 HP or so from having a cylinder not fire, then I am skeptical that others can discern a difference of only 10 hp without using instrumentation.

When I added Heads/cam/RR/Headers/etc, it gave me an additional 150 rwhp (instrumentation via before/after dyno). Surprisingly, the additional 150 didn't "feel" that much faster except that i noticed I had to shift gears much more quickly going down the track. The time slips showed that I was much faster too.

After the above mentioned mods, I added 3:55 gears. Interestingly, that mod gave me about the same sensation of increased power/speed as the heads/cam/etc, even though I wasn't going any faster or making any more power.

For me, this suggests that the human body is not a great instrument for determining small or changes acceleration. Or, maybe my senses are super-weak.

[Sybil TF]

I think i just answered a question that wasn't asked of me. Oh, well. Sorry.Yeah I deleted it . I realized I misunderstood his statement. Sometimes it is hard to read on this I phone lol. TB's are waste unless you have a SC or TT I gather. I see a sc in my future but won't bother until then.

[Sybil TF]

If I see a used set again for sale I'll just store them for future use. New ones are expensive. But they are so shiny lol.

[stuntman]

:( was looking forward to a back to back change on the dyno.

[Sybil TF]

:( was looking forward to a back to back change on the dyno.May happen if I see them again for sale. I'm going to get this car dyno tuned at some point. Wouldn't take much to bolt them on for a run. I have seen them for sale twice in a couple years so we'll see.

[MrCreosote]

I think the discussion should be relative to HP rather than "heads/cam/headers" which can mean anything.

Stock GTS, 450hp, 60mm, 2800mm**
Stock Gen4, 640hp, 75mm, 4400mm**

650/450 = 1.42
44/28 = 1.57

Interpolating: 545hp would be 3600mm** or 68mm diameter TB

[dave6666]

Let us know how that math works out for you on the dyno.

[MrCreosote]

I think it would be safe to say if you have a 640 HP "heads/cam/headers" that a 75mm TB would be appropriate.

[MrCreosote]

Would a "big" cam be something in the 230's?

[plumcrazy]

there was some back to back tests done by JD back in the day. only change was the TB's and it lost power. (same day,same dyno)

[Bill Pemberton]

Years ago, we did Dynos on 4 different Gen IIs ( race cars and stock ) and we saw declines in power , not increases. Bob W. may pop in here and verify , but I know the results were such that we did not recommend this to any of our customers. Keep in mind, this comment is all in relation to Gen II Snakes.

[MrCreosote]

Viper did some changes on the intakes through the generations, so Gen II is probably not very good. (I was thinking with the long plenum, developing some "nozzle velocity" at the TB's may help the rear runner flow.)

Has anyone cut open a Gen II plenum? I'd like to see that pic (!) I wonder what it would cost to get an industrial X-ray of one? (haha - but don't laugh. At Robershaw controls, we were trying to reverse engineer a competitor's stove spark ignition module which was potted with black epoxy. Since there are only about 10 discrete components on such a circuit, my job was to take a bunch of X-rays using the company's industrial X-ray machine. It was very cool forensics and I was able to reconstruct their circuit.)

Bill, wow, even the race cars. Were these the bigger TV's (70 max) or the really, really bigger ones? (75 min?)

[Bill Pemberton]

3 were race cars ------ and hard to remember the size we checked clear back then , but it was not of benefit to any of them.

[Red Snake]

N/A or FI matters also. With FI and 10 lbs of boost the larger TBs could be beneficial.

[SmoknTires]

I played with this quite a bit myself on my early cars. On my 2 stock cars (different Gens), including those with minor bolt on mods (headers, exhaust, etc...), lost power every time. We put it up on the dyno before and after, and again after removal. Definitely hurt performance. I remember exploring with Dick W and gang at the time, it was clear it slowed air velocity causing the decline in HP.

[plumcrazy]

N/A or FI matters also. With FI and 10 lbs of boost the larger TBs could be beneficial.

JD's back to back tests proved this not to be true.