Anyone directly dynoed a throttle body swap or know of another mag article that does the the same?

I was browsing my old car mag collection the other day looking for LT1 related stuff and stumbled on a LT1 bolt on test done in the May 97 issue of Chevy High Performance.

In it they dynoed a B&B catback, AS&M CAI, and a AS&M 52mm TB.

96 Z28 test car (no indication of A4 or M6). 251rwhp/296ft-lbs baseline. The gains from the CAI was about what I kinda expected, 9rwhp and 7 ft-lbs, back to the stock intake setup and adding the catback yeilded less that I was expecting, 5 rwhp and 8 ft-lbs. Adding the AS&M CAI back on w/ the catback yeilded 15 rwhp and 10 ft-lbs over the baseline (so the CAI was worth about the same as it was w/ the stock exhaust 9-10 rwhp). (266 rwhp/306 ft-lbs at this point).

The thing in the article that got me a bit was the addition of the 52mm TB, I've been of the camp (that seems to be the norm on this site) that figures a new TB would have been worth maybe 3-5 rwhp, and thus not worth the coin. But here it upped output to 276 rwhp, 320 ft-lbs. That's 10 rwhp and 14 ft-lbs over the CAI and exhaust alone. Pretty decent gain IMO. W/ the 52mm ported TBs on Ebay for $150-ish recently this has kinda interested me in snagging one, pretty decent power gain for the money in their case.

Anyone dyno a TB swap themselves or seen another mag article that dynoed them? Just curious, only other results I found quickly searching this site were from Ion/MadZ28 that showed a loss on a heads/cam car IIRC that just plain doesn't seem right...

I scanned the first page of the article w/ the power mods, unfortunately they didn't get to the headers, really would have liked to see the dyno results for those... Bandwidth may cut out...
http://bellsouthpwp.net/j/s/jstriet/LT1article1.jpg

 

Magazine tests are notoriously skewed remeber the aftermarket is where they get their money. Subscriptions are not how magazines make their money advertizing dollars are. If you think a larger TB is necessary just check for vacuum at WOT you want it low as possible. The old rules were if with a carb you had more than 1.5" at WOT you needed a larger carb, for the street, for race applications they said .5", since our TB is dry we want to shoot for the .5" number. This is an actual measurement representing any intake restriction you might have then it is up to you to figure out exactly what is the restriction.

 

Yeah I thought of that but the results for the other two bolt ons were in range/or actually lower than most would expect. Surely they would inflate the numbers for everything if they were going to be shady about it...

I may try the vacuum reading, shouldn't be too hard.

EDIT - The dyno results from the article are from Pro Dyno in Arizona that has a good rep over on LS1Tech and other sites I believe, I'm not buying the inflated numbers for the article bit. Not w/ the results from the other bolt-ons...

 

Ya mags do up the #s sometimes for ads. If i was you i would research porting your tb to 52mm if you really want one. I wouldn't bother untill heads and cam come along though.

 

I have always been skeptical about a 52mm only gaining 2-3HP, being not worth it, blah blah etc

I would like to see someone's personal before/after dyno's...

 

well the whole article is skeptical since the baseline FWHP of the car was approx. 295HP/345TQ....stock is approx.285HP/325TQ

 

Looks about normal to me, considering every car will differ slightly.

 

In my mildly cammed(ZZ3 cam) Caprice I did some logging last night, I was maxing out the stock injectors at the top of third but rarely did the vacuum exceed 1", my intake in front of the TB is as good as it gets though a RAISS, it is a scoop underhood which runs cold/"ramair" up over the core support and contains it around the cone filter which is directly mounted to the f-body MAF then a 3-4" long boot to the TB. I have an airfoil I got cheap mounted to a tock TB.
Injector dutycycles were staying over 100% not just a blip up there.

 

Say huh? The baseline rearwheel numbers they listed are right smack dab in the middle of the accepted norms for a stock LT1 dyno... 250rwhp/290ish ft-lbs is what most people post for stock dynos around here.

Your torque numbers seem slightly low on the other hand for a couple mods (looking at the chart your's looks pretty damn rich though...)

 

Any other comments or personal experience? I am thinking about pickup up a 52mm over my stocker and its tough since I seem articles like this but then dyno results from Madolf showing 10rwhp loss on a cam'd car.

-Dustin-

 

A larger TB will NOT hurt the preformance. It may not help but it don't hurt.

 

I was wondering cause Madwolf reported a 10rwhp/18rwtq loss across the board with his 233/239 cam with bolt on's. It makes me just want to stick with a stocker.

I worry about velocity vs volume and where the two are optimized. Or if that even matters.

-Dustin-

 

If ya don't have enough size to replace the air being used it won't make HP. The LT1 plenum is small and ya need to put the air back as it's being used.
Velocity don't count as long as there is enough movement to get the air in. Ya could have a lot of velocity and not much air getting into the plentum and the air going crazy inside after it hit's the back wall from the velocity. Ya need to figure how much air your engine uses at a given RPM if ya are trying to get buy on a short dollar and not buying one.
I have run two 1060CFM 4 hole TB's on a 408CID turning 7500RPM's. One didn't get it done the car just didn't run. It also needed more fuel with the addition of the second TB.

 

Well how do I figure how much I am using? I basically have all the bolt on's except a larger TB. I have some extra money that I could get one, but I like to invest my money wisely into the car.

I wish someone would just do a before after dyno on a bolt on car that isnt a magazine.

I could see $150-200 much better spent towards a Converter or Cam if I am only going to get 3-5hp.

-Dustin-

 

Just yesterday I swapped from a airfoiled stocker to a 58mm, not that I think I need that much but I got a good deal on it and am looking for every last edge in going for a new PB this weekend and it might even end up being a stock heads/aftermarket cam b-body record. Frankly I can not feel any real power gain though lowend throttle response is vastly changed. Where I used to cruise at 13% throttle now it is well down in the single digits and the sligtest throttle movement results in a lot more acceleration because the larger bores allow a lot more are at the same angle. Like I said though no noticable WOT difference. Not seeing anything really different in my MAP or AFGS either.