Dyno #'s This Weekend For 308 Intake/TB Mod

The whole test for the TB mod is meaningless other than having fun with air filters.

If you don't match the pleniums diamteter to the larger TB it will create turbulence at the lip where the air goes in and yes reduce horsepower which is exactly what happened.

The plenium intake diameter must match that of the larger TB for the TB boring mod to work its that simple.

 

You would at the rear wheels. Lighter flywheel=less power loss to rotating mass.

 

It will also be interesting to see if putting a stock TB on Tommy's bored plenum comes out as much difference. Since the plenum will be LARGER than the stock TB, it won't have as much bad turbulence as the other way around.

 

The lip on the stock intake is the killer I have to believe. The 348's have a massive intake mating hole on the intake. Even after increasing the bore on my TB it was still 10-15mm larger in all direction so no plenum porting was needed. This in my mind is the reason that you didn't see a gain.

I actually learned this the hardway as well with my old TransAm build up. I replaced the stock TPI throttle boddy with an oversized one from SLP when I rebuild the engine and never checked to see if the plenum was big enough on the intake. One day I noticed the lip and spent about a day removing it. It made a difference on that car so I am pretty sure it will on your's as well.

Thanks again for doing this guys! Its always great to see people get out and really tune their cars.

 

Matching up the manifold will make a HUGE differance. In fact many header designs have a lip on the outflow side of mating surfaces designed in as an anti-reversion "check valve" to prevent exaust gasses from backing up into the cylinder with high duration cams.
I.E. if possible make the manifold hole slightly larger that the TB. Bore the gasket as well.

 

How big is a HUGE difference? 6HP? Its not like the lip is hiding 50HP in there. Once it is port matched then they will get the lost HP back. The torque curve will take a hit either way and thats all that matters, the HP is unimportant when you pull away from a light and mat it - BOOOOOOOOOG, count to 10 then you go, lets see the graphs before and after as well. Bottom line - waste of money. Kudos for tuning? Not from me, anyone with experience tuning any car knows the TB is the wrong place to look for gains on a stock engine especially with the CIS cork in front of it. This isnt tuning, its called going against good advice. Also, using a dyno with the wrong calibration for the final drive ratio of the car is basically a waste of time, could have gotten better results with a G-Tech pro and your buttometer.

 

Well, your posting certainly was. But the dyno session was NOT a waste of time for the two of us who participated in it; you're not the one to judge. Since we were just checking whether a change such as an oil filter swap makes a positive, negative or no difference, it doesn't matter if you use the wrong gear or not... it still told us what we wanted to know.

 

I just logged on a minute ago, so this is new info. Thanks to the both of you for the dyno time, cost and effort.
As I mentioned earlier, the plenum opening is quite important to the total flow passage, and IMO would easily cause a drop in power.

"Matching up the manifold will make a HUGE differance. In fact many header designs have a lip on the outflow side of mating surfaces designed in as an anti-reversion "check valve" to prevent exaust gasses from backing up into the cylinder with high duration cams.
I.E. if possible make the manifold hole slightly larger that the TB. Bore the gasket as well.LIGHTGUY"
This is probably as close to an explanation as there is as to what very probably was occuring. In the observation of laminar flow, running off, or a step down, will not disrupt flow, as the area in transition tends to become "dead", or non moving, and therefore inert.
Running into a lip, however has a very detrimental effect in flow. The stream hits the lip, and this causes a tumbling motion to occur, well into the main portion of the stream, thus reducing the total flow. A lip all of the way around will actually tend to "choke" the flow.
The anti reversion lip mentioned is a great example. The exhaust gas flows easily into a larger space. If the flow is reversed, the turbulance caused by the lip has such a dramatic effect on the flow as to reduce, if not eliminate the reversion.
Much of this can be observed by watching a stream, or river, as the flow makes its way around rocks and holes.
Looking forward to seeing the test with the plenum!!!
In the air filter spacer topic:
A spacer placed between the top, or lid, and the filter element is the tip. Longer screws are of course necessary. This mod helps the air get to the element in the area that is flat, and IMO is too close to the element. I have checked (with clay) the bonnet clearance, and find it is often 5/8", so there is usually room. This area is right over the air door, so it needs all the help it can get.
BTW: Do you have air/fuel readouts on the different runs?

 

Oh yeah, on the topic of dyno/gear choices:
Most operators will want you to run in 4th gear, as that is the closest to 1:1 available. They often enter it as 1:1.
HOWEVER. This is where the differances can really crop up. A bit of research I did a while back showed that the overall final drive ratios ran the gamut.

4th gear ratio Crown Gear ratio overall final drive ratio in 4th
308 GT 1.12 17:63 1:461
308 Quattro USA 1:12 16:65 1:455
308 Euro Quattro 1:24 17:65 1:428
308 Challenge 1:12 17:63 1:415
328 Euro 1:12 17:65 1:428
328 US 1.12 16:65 1:4550
328 Challenge 1:12 17:63 1:415
81 Mondy USA 1.24 17:63 1.461
82 MondyQVEuro 1:24 16:65 1:505
85 3.2 Mondy 1:24 16:65 1.505

With the actual drive ratios running from 1:415 to 1:505, I can't help but wonder as to theaccuracy. This is based on the fact the dyno operates by accelerating a drum (850lbs), and the comparison being time it takes to reach a speed is how they calculate the power output.
My question? Gear advantage (torque multiplication). How do they calculate this?
And what about tire diameter?
Kermit

 

One of my main points Mike is if you are doing dyno time free or not why not do it right? As the saying goes if its worth doing, its worth doing right. The mis-calibrated dyno told you nothing more than your butt did and what most people here believed anyway and thats why it was almost a useless exercise aside from getting to stand beside the car and watch. Call it judging if you like, Im stating fact from experience as this is my field of expertise not to mention the purpose of this thread is to debunk claims, thats hard to do if you dont test properly.

 

Not so in my car. There is less than 1/8" clearance between the bonnet grating and my airbox lid. If I don't have the airbox firmly down all the way, it has rubbed and left a mark.

Not on the earliest pulls, and not being knowlegeable about dyno runs and equipment at the time, I don't think the ones we have are meaningful anyway, since the guy put his sensor in the tailpipe and I have a cat again (Hyperflow) rather than a test pipe... I now understand that it needs to be ahead of the cat, like off the O2 sensor or using a test pipe. Tommy's car does have a test pipe, so we'll get info off of that when we run the tests with his car.

 

No -- the purpose of this thread is NOT to debunk claims, neither to prove them. The purpose of this thread and activity is to gather data. The results may show claims of hp improvement for various items to be false or they may show them to be accurate. Tommy and I are neutral, but certainly hopeful that we'll find out what works and what doesn't.

 

4th in a 308 is 1:1 (or supposed to be), 5th is overdrive. We always used 4th in our pulls on Dyno Day with the club. 2500 RPM to redline or less.

 

You are right again...congratulations.

Now, maybe us more dumber people can do what we's want with our own money

Thanks for sharing your experience Tom & Mike.

 

You know, I would have expected this crap on the Pcar thread, or some ricer forum, but not here. Mike and Tom have simply tried to use time, energy, money, and materials to see if anything gives these cars some added power, and here again we have a thread 5 pages long and most of it is almost derogatory. Like our mothers used to say, if you dont have anything good to say, keep your mouth shut. I suppose if one of thier cars blew up on the dyno some of you would laugh? Toms car broke down, he never made it to the dyno, And Sloan offers his little smiley faces like a two year old.

Its really easy to sit there at your computers coming across like big know it alls, but without some documented evidence, to just debunk something out of hand seems rather disengenuous. These guys attempted a test, apparently the only ones willing, and from the outset some of you been kicking them and have been of absolutely no benefit to this thread at all. Now that the results are back some of you want to kick them for not knowing more about the dyno. You know what, go to hell. Why didnt you offer advise somewhere during the week leading up to this? Where were you then? Oh yeah, making a big noise about how it wouldnt work. Like a bunch of little kids, one of you cant stand it cuz his enemy Kermit had something to do with it, gotta kick dirt, and some others just want to be jerks. Sorry for ruffling feathers, its just how im seeing it. And you know what? Its not just this thread, its just about anything technical. So what now, Mike and Tom should just appologise to everyone here for trying?

Oh and by the way. They do make load absorbing dynomometers. They hold the wheels at speed and measure true BHP at the wheels, not some phony number calculated off inertia. You can hold your foot to the floor and the dyno will not allow it to move up in rpm, but can hold it steady at any speed or throttle position and read real BHP. And it wont matter which flippin gear your in. I think these inertia ones are good for seeing a change, but the actual numbers are not that realistic. I also do not believe there is a flat 17% power loss, but a steady relatively equal loss of somewhere around 35 BHP. Just MHO.

Mike and Tom, you guys should deserve praise, and I am here to say, as are a few others, thanks for your effort. Here is to hoping you go back with that manifold matched up and try it again. And again, and again, and again. There is power in these CSI motors, its just hiding. And its shouldnt be that difficult to find some combination that wakes it up without totally starting over with $$$$$$ worth of new systems.

 

pardon the slight hijack---

can anyone "feel" a K&N diff over paper filters? I saw the prices and I'm like, geez, they're real fond of them.......

 

Nah, you're not going to feel 3 hp (or even 5hp as some have said on bigger motors), but on my 308QV I *can* hear a sound difference as air gets sucked through that scoop. It's subtle, but I like it.

I guess what we're trying to do is find out how to get 3hp here, 2hp there, 5hp somewhere else.... pretty soon adding up to something more substantial overall and giving the cars a bit of a "wake up" as Paul Colberg said.

Mike

 

Tommy & Mike,
This is a great thread, very educational. Even if you used the wrong gear for absolute measurement accuracy, your relative accuracy from one run to the next is fine and provides us all with very valuable insight. Thanks for not only taking the time to do it, but to post it and then dodge all the bullets!

I too think that you will not see a 6 HP loss one you are running with the plenum matched to the TB. But I'm not sure you will see much of a gain either. I'm very interested to see what happens!

FWIW, I did not take Sloan's smiley face as anything more than a little gentle ribbing. We're all adults here. If I had the plenum on my car and it dynoed less than expected, I would expect my pals to give me a little ribbing. I don't think he meant for it to come off as mean. At the end of the day we are all Ferrari guys and this is good info for all of us. Everybody take a deep breath and play nice!

Birdman

 

Yeah, us too. When we started this process and scheduled the dyno, we didn't realize that swapping the plenums was not as trivial as swapping the throttle bodies. We'll know more when Tommy's car is up here in a couple of weeks and we go at it again. And thankfully, Tommy is much more handy with a wrench than I am!

 

Did you ever get a chance to put these parts on a Flow Bench?