Pretty disappointed after my last trip to the track...

Previous best was 12.328 @ 114.62 with a 1.877 60'

Best run last trip was 12.314 @ 114.68 with a 1.857 60'

Between those trips I added a FTRA and Shaner S3 TB, so I was hoping to gain 2 tenths and 2 mph or so. But after taking into account the better 60' of the latter trip, I really didn't gain squat. Also, I had changed plugs to NGK TR55s and cleaned the K&N which had been pretty dirty before...

To address the obvious, weather was very similar both trips, around 80 with high humidity.

Any ideas what could be going on here? My car has about 35,000 miles and I did have the !FRA mod before adding the FTRA. I can see how maybe I wouldn't gain much with the FTRA over the !FRA, but I really thought the TB would give me something. Am I wasting my time with a ported stock TB, should I have gone to a 90 mm?

 

Have you had the car tuned with any of your mods?

 

well here's a stab at it then.

1. Yes the weather........ Evan though you say similar it probably wouldn't take much to make a variance, even more so as the changes you did where only very minor. This should always be counted as an issue.

2. Track prep. Again when you're talking tenths and thousanths of a second this is vital and WILL have a bearing on it.

3. Car prep, where you running exactly the same? No of course not there are hundreds of components that could, will and do have a bearing on it. Obviously tyre pressure is a key factor, but even tread wear could have a bearing. Also fuel, in terms of how much (weight) in the car and grade, is it 100% the same as previous, or is it mearly 'advertised' as the same grade. There will be variance from petrol station to petrol station, even different fuel delivery from the same source. It should of course only be a minor difference but without checking it you should at least consider it.

3. The mods, well you list 3 mods/changes, only 1 of which is really likely to have any affect.

K&N - the stock paper filter will supply enough air for 500bhp n/a so a dirty K&N will not likely have any bearing on performance of the car, just the 'filtering' abilty of the K&N, for this is the main reason they have to be cleaned.

FTRA - Ram air is pretty pointless and a very good marketing ploy. You can not easily force air into an engine without the aide of FI (turbo or supercharger). At 150mph it may be measurable, at 200mph it will become significant enough to aide in power but there are very little gains this side of 350mph. So it is not suprising there is little or no gain. Any gain that people get from such a mod is due to so called cool air ducts or air box resonance, neither are directly rerlated to compressing air and forcing it into an engine intake manifold.

Cool air is also not as affective as many people beleive. Remeber as the car moves so does the air in the engine bay. Even under bonnet temperatures are not that bad when moving. So if air is being taken from infront of the radiator any cool air duct will be of little use.

Also your car is not in a vacuumed area so even if the air intake is not directly in the airflow there will still be plenty of available air.

TB - I'm not familar with the one you list, assuming it's bigger than stock then it certainly has the potential to make a little more power. However if the TB is not matched correctly to the rest of the setup and even more importantly not having the car tuned with the now increased availability of air flow thru the TB it will likely yeild little or nothing, or maybe even reduce performance.

Also last but by no means least. IN FACT THIS IS LIKELY THE BIGGEST FACTOR FOR ANY PERFORMANCE ENTHUSTIAST. And this critical component is YOU or more specifically the driver. Being a human and not a robot it is very unlikey, no matter how good you are that you can deliver 100% the same performance and reaction times all of the time. In most cases the dirver should hold up their hands and except 90% of the blame for any variance in results, it may not be something you like but it is almost certainly true.

Remember the faster you go the harder it will be to go quicker, each tenth of a second will start and cost more and more in terms of bhp.

Get a good tune and see if it helps, just don't expect too much from too little.


EDIT: Just noticed, the TB was only ported not bigger. Well if you where lucky you may have picked up 1 real world BHP (not rwhp) with the mods done. A bigger TB as I said above has the potential for some power but I doubt it will really be enough power to make any real odds ET wise. If you really want a power hike look into FI, it can be costly but no you have almost 400rwhp and further bhp mods are going to cost regardless of what they are.

 

I don't think you'll see a ton of difference with a ported tb until you get an ls6 intake. The stock tb and intake are pretty well matched. If the car is already pulling in all the air it can through the intake, it's not gonna be able to pull any more until that's replaced.

 

if its an 02 Fbody it will already have the Ls6 type intake manifold.

 

 

Good points there... Yes, the car was tuned by MTI but that was before the TB and FTRA. I can see how the FTRA may not have added much for me... but I had heard great things about ported TBs and expected a marginal gain between the two of them.

One variable mentioned I didn't consider might be the gas, I ran Diamond Shamrock last trip which in my mind is a slightly lower grade gas than Shell and others that I typically use - especially if I know I'm going to the track - maybe that cost me slightly. Also, the weather might have played a larger factor that I initially considered because it was damn humid last trip, maybe more so than the prior.

Before recently, I didn't even bother with bolt-ons other than lid and exhaust 'cause I always knew it takes serious mods to make real power (i.e. cam, heads, nitrous, supercharger, etc.). Wish I hadn't wasted my money and rather just continued to save for the AFR heads. That comes next.

Taintedmeat, I see you're from Austin too

 

I have the same name on afbforums.com

If you're not a member you should be, it's "Austin F-Body"