i see throttle bodies with twin 52mm and 58mm
i have a 89 tpi 305 , im wondering if i should go with the bigger one cause its only 10 bucks more or will that hinder performance?

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-wikdmaro

 

more air flow is best. at wot does your engine
need more? stock cam? stock cylinder heads?
if so, you may notice a betterment, but when
adding cams, heads, intakes.. itll work more
so than the 48mm unit. wot performance is
where this is more applicable. just like the
larger MAF sensors. under wot, no difference.
airdeano

 

a bigger TB isn't always better, a bigger TB in the wrong setup will hurt throttle response. If you are running a stock 305 u don't need a bigger TB...

------------------
Check out MyGTA Nicknamed:The Big Red Machine
***AOL IM ClarkeMustGoNow***
Moderator at www.transamgta.com
"What does not kill us only makes us stronger"

Tony

 

ya a 58mm Throttle Body flows something like 1000 CFM.

------------------
- David
88' GTA 5.7L TPI MODS---> air foil, K&N, Shift Kit, 180* therm, TB bypass, Gutted CAT, Flowmaster 80 Series

http://www.geocities.com/david_angel_16

 

WEll here we go again.
If you have a MAF car, a 58mm will be fine, but you will need more fuel and yes you will lose some low end grunt, but you will get more HP up top. Thinking on these lines if you have a stock intake manifold and runners with a stock cam on a 350 or 305 you dont nedd it. IT will just cause you to not have what the engine was made to have. Torque at low RPMs.
Now if you want to slab a larger cam, SLP or other style of runners that has a shorter length, not Long Tubes, then fine go ahead and get the 58mm, but you will have a lot more porting work to do on the plenum.
I had a 355 TPI with SLP cam Runners, INtake POrt matched to all components and a slight porting job on the intake manifold. MAde a HUGE difference when I put the 58mm on comapred to the 48mm stock, though I reported the plenum again to match it. THe moral here is that I could use it.
THough if you have a Speed density system forget it. You will ose vacume in the intake and you will 100% for sure need a custom prom to compensate.

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89 Trans Am Turbo 3.8L All stock 43,000 miles #1053 of 1555

Past Thirdgen:
86 Trans Am w/ built 355TPI with SLP goodies and too much other stuff to List. One sweet *** car, wish I would have had a good enough Job to pay insurance on three cars so I could keep it, but for a 89 Turbo Trans Am w/ Low miles, I think I made the right choice!

 

Do not buy a larger throttle body. Your throttle body flows 650 cfm. You could probably spin your 305 up to 6800 rpm before your throttle body becomes a restriction. They put the 48mm on the Ram Jet 502. It has more plenum volume, but come on....
Your 305 makes me sad.

------------------
355 c.i.
Dart 180 Heads
Lunati 224/224 cam
Harland Sharp 1.5 rockers
Performer RPM Manifold
Holley 600 cfm double pumper
Hooker Super Competition Headers
Flowmaster Exhaust
Competition Engineering Sub-frame connectors
Super T-10
GM posi 3.42 rear
Hurst Roll Control
13.9@102

 

Yes, don't switch. It's the same as a 650 cfm carb on a 305. Plenty of flow.

 

No, it's notthe same as a 650 carb. Carbs are rated wet flow (with fuel) TB's are rated dry flow.

 

if u wanna buy something just to say u have it or whatever. or to maybe gain some, buy the 52mm

------------------
- David
88' GTA 5.7L TPI MODS---> air foil, K&N, Shift Kit, 180* therm, TB bypass, Gutted CAT, Flowmaster 80 Series

http://www.geocities.com/david_angel_16

 

"Your 305 makes me sad."

Obnoxious remarks from know-it-alls make me sad...

Sorry to the rest of the board if this starts a flame war, it was just an unneeded comment on his part.

-Reno

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89 Formula 350
"This is how you remind me of what I really am..." - Nickelback

[This message has been edited by Reno (edited October 25, 2001).]

 

LOL your 355 makes me SICK, all that work and only 13.9's? BWHAHAHAH! my stock L98(yep bone stock, plenum and valve covers haven't been lifted) runs a best of 13.89 with just bolt ons, why u raggin on his 305, i personally don't like 305's but i know quite a few that would put your "oh-soooo-superior" 355 to shame

------------------
Check out MyGTA Nicknamed:The Big Red Machine
***AOL IM ClarkeMustGoNow***
Moderator at www.transamgta.com
"What does not kill us only makes us stronger"

Tony

[This message has been edited by fly89gta (edited October 25, 2001).]

 

Oh so so now I get it. YOu "bone stock" motor has bolt ons..... That means not stock. Then Ofcourse if I was going to get in on this... All you V8s make me sick. All those extra cubes and you cant out run a V6? That is crap.
You never see me make dumb ccomments like that just because my car is faster than someone elses on this board. Holy crap guys come on we are here to help each other out not flame on each other.




------------------
89 Trans Am Turbo 3.8L All stock 43,000 miles #1053 of 1555

Past Thirdgen:
86 Trans Am w/ built 355TPI with SLP goodies and too much other stuff to List. One sweet *** car, wish I would have had a good enough Job to pay insurance on three cars so I could keep it, but for a 89 Turbo Trans Am w/ Low miles, I think I made the right choice!

 

you do not require a larger throttle body yet. until the rest of your induction system can flow enough to use the additional flow a 52 or 58mm TB could provide. when doing any induction system upgrade, you have to weigh two factors, air volume and air velocity. sure a 58mm TB can flow more CFM then a 48 or 52 at the same velocity, but how fast can your engine suck in the air? For a smaller engine closer to stock that doesnt have a huge amount of open valve time, the fast you get the air in the better. A smaller TB will help to increase the incoming air's velocity into the plenum and therefore the cylinders. If you have a 58mm TB your airflow will be lazy and slow. you can suck more air in but at a slower velocity so the air wont rush as quickly into the cylinders leaving them underfilled. thats why you should stick with the smaller TB for now.

 

BTW Kyle F. I can outrun your V6. How much did you spend on your car? Probably about $10,000 or more. I have less then $7,000 in my car including the purchase price of the vehicle. Wana run?

 

You losers are wrecking this board with your stupidity and ignorance. I actually know people that have thirdgen's that won't post here because of this nonsense. If you can't add something to a post don't reply. If it actually physically/emotionally pains you to answer to a post, I suggest you seek help. Having said that, I believe a 48mm TB will support any power a 305 will put out and a change to a larger TB would be a waste of $.

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89GTA-The Driver
92Z28-The Lawn Ornament

"Sunday Money"

 

I was defending the 305 owner, because the guy that built the 355 should be running WAY better times than what he has with all that work. What don't u understand about waht i said, the engine is STOCK, haven't lifted the covers or plenum, what i meant by bolt ons is exhaust chip shiftkit etc, but the engine is stock..got it???

 

the ONLY reason why i fired back was because there was no reason for TPI Guy to rag on that guys 305, he was asking a simple question, and for someone that has all that work done to his car and pulling those times he has no right to say anything...

ok i'm done now

 

I agree don't change it at all, but if u are going to anyway, go with the 52mm.

------------------
89 RS

STILL Looking For:
An 87 IROC-Z28 350 TPI

Yeah I have an RS, but I want an IROC-Z!!

 

Once again we reach the et v. MPH dilemna.
You very well may run a 13.89. You also have an automatic transmission with a stall converter, and probably bolted on a set of slicks. I know that you did this at a much slower mph also.That means you aren't making as much power.

I ran a 13.9 @ 102. I have a stick with a 2.66 1st, Falkan 245's, and a 2.3 60'. I refuse to run my car in any way other than what it will run on the street. That means no slicks, no taking off my serp belt, no open exhaust. It might not beat your 13.89 at the track, but on the street....

In my own defense, I had a 305. I hated it. It wasn't good at anything. It wasn't good at making power, it wasn't good at getting gas mileage. Hey, if you enjoy being second place, by all means, the 305 is the way to go, but if you are in the market for speed, for the money, it makes more economical sense to build a 350, and I don't think you will find too many people who are going to argue that point with me. I know because I rebuilt them both.

 

i wasn't ragging on you saying "haha my car is faster" and like i said, you MPH shows your car is MORE powerful. I agree with the slicks thing, i don't run them either, just drag radials. BTW my tq converter is stock. That 2.3 60' time is killing you, but again u have a stick so i understand

Knock that down to like a 2.0 shiiiiiit u have low 13's on your hands

 

Actually I have $4000 investede in mine. After about $3000 worth of mods I will be in the low 11's. Sorry its the truth you should see what some of these guys with Grand Nats have done for around $1500. Starting out with intercooled forced inductions is a great benifit. Though I think you mis understood me. I know I can out run a lot of cars on this board, and I know some are faster than me. What I mean by what I said was that we should not be that way. Hear people say that the 305 is someone elses car makes them sick. Thats just stupid.
Though hey... you want to run, maybe we will hit the same track one day. Who knows if we do maybe we can trade a few secrets... thats what I am here for.
BAck on topic
I still say the only reason you will ever need to switch Throttle bodies on a 305 is if you port out the whole intake track and port match them to a a shorter runner like the SLPs. Then you need a cam that will match you new intakes power band. Once you have that then your 305 will need more air and fuel to make its full potential of power. I would invest elsewhere first. YOu will getm more power out of a set of headers with a Y-pipe like headmen or Eldelbrock TES

 

Ok, going back to the actually topic about TBs. I've read one an article I think in HPP about TPI mods it stated that if you do go to a bigger TB without other mods the car will get a dead spot off the start line from to much air. So I would say 52 or 58mm tb would be a little to much for a 305 unless you have other mods. Wouldn't this also mess with your air/fuel ratio?

 

I believe, if you were trying to quote me, you meant to say "Your 305 makes me sad" to which fly89GTA responded, to me, "Your 355 makes me sick" There are very few people, with the exception of Willie and a few others, that actually prefer the 305 to the 350.

My point is this: If you want to go faster, you have to do the work. You want to go faster, so you bolt a throttle body onto your 305. You choose the throttle body because, hey, it doesn't get much easier to put something on than that ... but what most people really want is more cubes, but they don't want to take the time to figure out how to do it because it's really hard work to put a new engine in ... and most people want the instant gratification they receive from opening up a box and bolting a TB on their 305. I know everyone has a different story, and a lot of you have some very valid reasons for retaining the 305, but for the most part people are too lazy/afraid to do the work.

 

TPI Guy: you said u had a 305 and hated it, what was it? LG4? LO3? LB9?

 

To tell you the truth, I don't know. It was from a 1986 caprice I think. I broke my fourth bone stock 250 (I have a 1973 nova), threw the camshaft through the side of the block, and needed an engine fast. It had a one piece rear with the old style intake manifold bolt pattern. I had a performer manifold/cam, headers, a holley 600 4150. It had 1.84/1.5 valves in the heads, and a bucket of carbon in the lifter valley. Even though it was slow, it was dependable. It was only in there a year before it got yanked, though.

 

how does a simple question turn into this geez hell yeah I spend the kind of money it cost for a tb I want instant gratification
I thought these boards were for infomation and help hey maybe a question about a tb leads into more questions which leads a person to build a twin turbo set up but you got to start somewhere it just pisses me off when someone asks a question and they get crapped on all right I am getting off the soapbox

 

IN MY OPINION.. not a fact or anything cuz anything's possible with $.. neways.. a 305 won't ever suck enough air in unless u'r reaching high rpms to even consider changing the tb.. but to get into those hight rpms on a tpi, well.. everything has to be ported and change the runners and manifold and heads and cam and by that time you should know enough to know what the best tb would be.. if you're looking to get the mod now cuz u can so you can start off by that and move up in the mods, well.. i'd say start by the cam or the heads.. alot more hp increase in that.. cam would be where i start..
and now.. for the 305 thing.. wtf is wrong with a 305?!.. sure it dosn't have cubs and from factory is a pathetic motor.. (compared to "other" motors with the same cubs (302)) neways.. you can get 305's pretty decent.. like 350 hp range.. why keep it?.. cuz it's more challenging to get a 305 to move then a 350.. EVERYBODY AND THEIR GRANDMOTHER has a 350 or 383.. if you want to go easy, go 350. I'd love to see a naturally aspired 305 doing 350 hp at 5000 rpm, 400 ft/torque at 4500.. i'd be more impressed then the one with the 350 doing that.

------------------
87 formula
LB9, Automatic
K&N
3" catback v-force muffler
Hypertech preformance chip

 

well that'd put a damper on my day how the hell did the camshaft go through the side of the block, i'd like to see that, probably look pretty cool

 

Here's one of the discussions on this subject we have had here. It pretty much hashes it over completely..

https://www.thirdgen.org/messgboard/...ML/003520.html

I might add to the discussion that I whole-heartedly agree that a 58mm TB is a useful and needed mod........... on the right combo. I stick to my point that the Plenum is not a storage area at WOT - it is a passage just like any other intake, thus, the need to not overkill the intake system with a TB that is too big.

EDIT: I guess I need to weigh in on the whole 305 issue..... The problem with the 305 is that the cylinders are too small. They shroud the valves too much. The only way to really make a 305 hang with comperable engines (size and total mods - wise) is to use a power adder.... You can get everything on a 305 to flow like gangbusters, but the intake valve is still shrouded like a ***** by the tiny bore...

------------------
1987 GTA L98 MD8
355, TFS Heads, LT4 Hot Cam
My GTA

The Minnesota F-body Club

[This message has been edited by Matt87GTA (edited October 26, 2001).]

 

It all started when I submersed my car in about 2 feet of standing water ...while the block was hot. (We got torrential rains and the drainage system was backed up ... all the streets flooded.) This severely weakened the block, and sucking water into the intake. I got it running again, and one night, while the engine was cold, I started it up, backed up, put it into first, drove about 30 feet, and chucked the thing through the block.

 

I will hopefully be taking my GTA to a chassis dyno soon. I have a stock 48mm TB and an LPE 58mm TB. I could run a test with each. Would anyone be interested in the results? What could be done to assure the tests are valid? Here is what the car has........

355 with "real" 10.8:1 compression
Ported SuperRam (base, runners, and plenum)
LPE ported Edelbrock RPM's
LPE "219" cam
AFR Hydra-Rev kit
Lightweight valvetrane
SLP 1 3/4 headers/dual cats/Flowmaster Force II
and a bunch of other stuff that I shouldn't have bought. Does anyone know of any Dynos in the MA or NH area?



------------------
89GTA-The Driver
92Z28-The Lawn Ornament

"Sunday Money"

 

Yes. Do that. Get those dyno numbers and post them!

 

I'd be VERY interested, since my setup is almost identical to your's. And I just recently went from a stock TB to an LPE 58mm.

------------------
89 IROC-SuperRammed 355 w/ AFR 190's and LPE 219/219 cam-http://www.geocities.com/buckeyeroc

 

I am very interested. Your mods are similar to those of my old 355, I though It helped a lot when I put my 58MM on, but I had portmatched the plenum to it. I thought I lost a little bottom end and gain a lot above 2500 rpm. I want to see if I was right.

------------------
89 Trans Am Turbo 3.8L All stock 43,000 miles #1053 of 1555

Past Thirdgen:
86 Trans Am w/ built 355TPI with SLP goodies and too much other stuff to List. One sweet *** car, wish I would have had a good enough Job to pay insurance on three cars so I could keep it, but for a 89 Turbo Trans Am w/ Low miles, I think I made the right choice!

 

Does anyone know of any chassis dynos in MA or NH?

------------------
89GTA-The Driver
92Z28-The Lawn Ornament

"Sunday Money"

 

thanks for everyones help !

 

To keep the test valid, don't change ANYTHING other than the TB between pulls on the dyno... Verify the air temperature, engine temperature, etc. before running the tests... Annotate everything (write it all down so you don't forget anything if the dyno doesn't record something).

Also, find someone with a 52mm TB to lend you and make a true 'final answer' test on this TB issue...... I would lend you mine if I were anywhere near you.... Try the stock TB with and without an airfoil as well.......

This will be really good information as it will be completely unbiased. We all will appreciate it....

Good Luck
Laterzzz

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1987 GTA L98 MD8
355, TFS Heads, LT4 Hot Cam
My GTA

The Minnesota F-body Club