Group Buy: 3x8 Throttle Body Mod + Plenum Mod

Not a bad idea but do you think some before and after dyno results would help bring in punters?

 

So kinda like this?

http://www.durable1.com/injectors.htm

 

Here's the deal: for years we've been hearing how much better a bored throttle body would be, and how restrictive the stock piece it. However, nobody's ever provided a dyno sheet that proves it. Even when we ask the vendors, there's nothing but excuses.

Show me a back-to-back same-day dyno sheet with a significant improvement, and I'll be interested.

 

I'm with Tillman. Didn't see any dyno results on the durable1 site either.

 

Absent any quantitative data, anyone BTDT that can provide a "seat of the pants" butt dyno perspective?

 

What leads you to believe that by solely increasing the size of the TB that there will be a gain in HP? This is not a derogatory question. Just looking for some facts or theory to back up the claim. (FYI - I'm running a 89mm TB on a 308QV, however, alot has been done to the engine including EFI).

 

I'd think that a *reasonable* first test would be to sand down the throttle bottle blades and replace the rounded screws with flat ones (counter sunk if possible) that hold the blades in place.

Those two non-destructive changes would give a larger effective TB and permit easy dyno testing.

If you get an HP boost from those two non-destructive changes, then it would be reasonable to think that boring out the TB itself just a bit would give a bit more HP, too.

Changing the screws and grinding down the stock TB blades could be performed by many F-chatters for no cost but their own time, too.

 

WASTE OF MONEY! The engineers toiled many hours through who knows how many calculations to make the induction system work together and there is a reason for the size they chose - not to slow the car down im sure. When ever any car recieves a larger t-body on a stock application, throttle response suffers and peak HP MIGHT improve at 8000rpm but torque will not, if anything torque will decrease as a result or you will just end up with the bragging rights that you have a pretty new part to talk about. I dont care what ferraris the seller of these parts has worked on, it has no relevance. Ever see those little fans you mount on the top of your carbs for improved HP and fuel consumption? Gimmick and people line up to get them - morons in my opinion. Putting a larger t-body on a 308 is like grabbing at straws for every little bit of power out of desperation only to realize the error once its on. Lets not forget the garbage up stream of the t-body that is the real restriction, put a bigger t-body in and leave the big fat cork in the system called the CIS flow meter.

 

You're not bothering anyone Steven. I think it's great that you're thinking of the rest of us.

I just personally have my doubts due to another vendor's lack of numbers, that's all.

 

A group buy is a nice gesture to save people money as long as they benefit from it as well as yourself. Only the seller will benefit in this case.

 

Guess he pulled his reply, it was there a second ago.

 

Yep, Kermit still has never provided it. Of course, dyno runs cost money...

Intuitively it sounds like a good idea, but the real-world benefit may be so minimal it won't be worth the $500 machining job plus the work or mechanic cost for the remove-and-replace.

 

I ,too, would be interested in some data before I would drop off any cash on such an upgrade. I ran a dyno in a tuning shop for a few years and I have to agree that the peak hp #s is not what you are looking for in an upgrade, it is the all the other info on the under the curve that is more important. That being said I trust dyno #s about as far as I can throw them, I have seen way too many charts in my day and they can be made to say anything that you would like them to say by a good dyno operator. None of this is in anyway directed to the companies listed above, I have no reason not to trust them. I agree the the first cork in that system is the CIS inlet/ flapper vavle and that changing things upstream of it is unlikely to create much change overall. You could start to measure air pressure in those area's before you go through all of the trouble to find the "corks" or you could pull the whole system off an flowbench it as a whole. I look forward to hearing what you find out, but remember that there is "no free lunch "with this stuff, That change will effect many other things in the chain, and not always for the better.

 

By the way, Dr. Tommy Cosgrove had Kermit do that work on his 308QV... and though I don't want to speak for him, he told me he wasn't sure he could tell any seat-of-the-pants difference at all. Tommy tracks his car quite a bit and pushes it hard, so I'd expect him to be able to tell.

 

His black 308 was running pretty well with us last Saturday, though!

 

Some more grunt in my 328 would be welcome, but from my hot rodding days I recall that one thing leads to another. You can reduce intake restriction, but without other mods downstream, one mod usually made things worse. If the motor can't suck in any more air for whatever reason, then more intake capacity just made throttle response worse and mid range power worse like Newman said. Anyone who claims they felt a power increase were generally suffering from a placebo effect.

Dave

 

I went from the stock 48mm TB to 52mm to 58mm back to 52mm on my 5.7 liter Corvette years ago. The 58mm was too much...the car was essentially at full throttle (with poor fuel mapping) with the accelerator pedal only half depressed...very poor throttle control, loss of torque, etc.

The 52mm was a subtle improvement over the stock 48, but the 58mm was too much and the car suffered.

Small changes in TB size can be beneficial, but I'd avoid large changes unless you are quite confident of what you're doing. There is a lot of the system that needs to be modified to make large TB changes worthwhile.

 

The problem I see with this is that the throttle body is not the limiting factor in flow of this system. It would seem to me that the big flapper in the CIS system to meter the fuel based on airflow is the restriction that limits airflow, not the throttle body. I'm sure this mod would help a teeny bit, but I doubt it would make enough difference to make it worth the effort.

Just my $.02.

Birdman

 

Using the engine-as-an-air-pump analogy, one might think that increasing the throttle body would naturally improve flow, assuming the stock throttle body produced a material restriction in air flow. However, in reality, the only way to increase HP is to get a bigger bang in the combustion chamber. Typically this is accomplished through a) removing obvious and material restrictions in air flow, b) increasing displacement, or c) pressurizing the intake charge. I expect the stock throttle body does not create and obvious and material restriction in flow that can be improved by simply upsizing - see other comments here re: trade off between throttle response, torque, etc. Other than improving the exhaust flow (catalytic converters, in contrast, do qualify as obvious and material restrictions on flow ), you're really left with b) or c) to get some bang for your buck and neither of these options is inexpensive.

If it seems too good to be true, then it likely is too good to be true.