Hello all,

I have a 1988 Pontiac Trans Am GTA with 115 000 original miles. I have the 5.0L LB9 Tuned Port Injection (TPI) engine, 4 speed automatic transmission (rebuild 10 000 miles ago to original specifications), 3.27 POSI and every options except leather interior.

I would like to do some modifications to it so I can match a stock 350 TPI car or even be a little better. If I could hit high 13 in the ¼ with the less money and troubles possible, I would stick with that for years to come and I would be very happy. Keep in mind this is my daily driver in the summer, and I live in Canada were it’s not as hot as in the USA…

Please list the mods in the order you would do them. I also would appreciate it if some of the experts here could give me the combo for an LB9 that would best suit my needs.

Thank you so much and see ya!

 

https://www.thirdgen.org/techbb2/sho...hreadid=275660

check out that thread for a bunch of answers on making your llb9 faster

 

One word buddy, nitrous!

Under a $1000, (cdn).

Easy to install and when u need it, press the button.

LB9GTA

 

In order to run 13's (without NOS) with a 305, you are going to have to do some serious mods and spend some big money.

1. free flowing intake, K&N air filter
2. Full exhaust, headers 3 inch catback
3. underdrive pulleys 3 piece billit
4. 1.6 roller rockers
5. gears, i would recommend 3.42's for a 305
6. stall converter, 2200-2600
7. ignition upgrades, aftermarket coil, MSD box, etc.
8. throttle body airfoil or 52mm tb
9. computer chip/dyno tune
10. lots of luck

 

big money? not hardly. you throw a cam/stall/gears in that car and it's on it's way, headers and catback and your there. throttle body you won't need until your deep into the 12's. how much experience with the lb9's do you really have? for under $1000, you got her done. you'd spend that on your car to get it into the 13's.

an lt1 hotcam can be had used for $100
alot of guys go with the edelbrock headers @ $330
hooker catback $215 (get the one for 83-85 305 HO)
a brand new b-stall converter(stock vette 1800stall) @ $120
gears and posi's are available ALL THE TIME on internet for CHEAP! 3.73 posi can be had for $150 used

total: $915

these are things that l98 cats would do too! and still only net mid 13's.

 

you forgot to add that with a bigger cam your gonna have to change valvesprings and install screw in studs. While your at it you might as well do some headwork, and, why bother to do that on a 115k motor. time for a short block! so it gets expensive quick. i was merely pointing out bolt ons that could be done to get into the 13's.

 

you don't have to put screw in studs and stiffer springs. i am running stock springs. no problems with valve float. besides, if you did that head work your talking about, the car is all of a sudden in the mid/low 13's. not worth it? hardly! there is nothing wrong with a 305 in the 13's. heck, you only have 3mph over me and i will gain that with the next few mods i am doing, and my whole motor will have cost MUCH less than those mods you have done to your car! you just gotta look around and find good deals on stuff man! heck, my 305 has forged rods in it cause they were only $120! BRAND NEW!

granted, i am carbed, and that makes aftermarket selection a bit easier on me, but non-the-less, the principals are the same.

 

I have been preaching on here for 2 years now that L98s are not the "wonder engines" that many people make them out to be and this thread and other threads on this board lately have only proven my point further. It is not that hard to get a 305 to go 13s be it carbed or injected.

The bottom line here is, that 305s just arent bad engines like many people claim. they have a smaller bore than a regular 350, well big deal, LS1s have a smaller bore too and i dont hear anyone talkin about LS1s being junk. In the real world, with street cars, with all things taken into account, the 45 inches difference between 305s and 350s just doesnt make that big of a difference. it seems that when both engines are modded the same, the 305 is usually about 2-4 tenths behind (until you get in the 12s, then the 350 advantage becomes more obvious, but lets all be honest with ourselves here, how many daily street thirdgens run 12s NA)

If you want to see how to get into the 13s with a 305 look at the sigs or PM the following guys (I'll include myself here because now i have a real exhasut and in a few weeks i will have a custom chip too which should only help my sitution)

TunedPort 335
mw66nova
Tim Burgess (12.7 NA with 160,000 mile short block)
Willie (currently in the 11s with a blower)
1MeanZ

 

If the intake to engine displacement were to match for both 305 and 350, the L98 would slam the 305 all day long. The intake system was designed for a 5.0 not the 5.7. I'm not saying the L98 is a 'wonder engine', but you can't compare the two engines with an intake built for one. That is as bad as comparing intakes with a cam built for one intake, of course it is going to make more power in xxxxRPM range, it was ground for that.

As for the LS1 being a smaller displacement than an L98...barely a difference. The difference is 4 cubic inches. Hardly enough to create a serious impact on the engine if you were to compare a 346ci GEN I block and 350ci GEN I block.

As for the original question. You would be better off get some really nice heads, LT1 cam, 2200 stall convertor, and bigger gears. Don't forget to get suspension mods for some traction, you will need to get out of the hole quickly in order to make mid-high 13s.

 

i've got bonestock suspension with home-cooked boxed lca's and a spohn non-adjustable panhard rod(which i doubt is doing anythig for traction) get some drag radials and be done with it. when you start making real power, get some lca's (i'll need em soon)

any 350 with the same mods as me wanna race, well bring it!

 

sa far as the ls1 goes, well, really apples to oranges, but what 1meanZ was trying to say is the bore/stroke combo is different to make up that 346 ci. it's got like a 3.85" bore or something like that.

 

I have gathered a couple of infos on the Internet. Can someone tell me if this combo would works well on my LB9? How much horsepower/torque and 1/4 time would be with this?

-Edelbrock's 1 5/8-inch headers
-4-inch exhaust system with a muffler with 2 exits
-JET Performance pulleys
-World Products' Torquer 305 head
-Cam: 206- to 218-degree intake, 212- to 226-degree exhaust duration, 0.480- to 0.520-inch lift, and a 112 LSA.

What would this cost me approximately? Is their cheaper way to hit high 13 with a NA 305 TPI?

 

Coated edelbrock headers $500
4 inch exuast $300
s/r torquers $1000
cam $250

whoopin up on 350's priceless

realisticly, this combo would put you well into the 13's providing you have the proper tune.

 

that 4" exhaust will cost you way more than $300! you might could get it for $300 USED. i went with true duals because i have longtube headers and i have access to a welder.

hedman longtube headers: $120
h-pipe: $33
hedman x-tensions: $25
2 1/2" exhaust tubing: $20
summit racing mufflers p/n 633222: $40 each

total: $278

the only reason i did it this way is cause it's most economical to me at this time in my life, it's really not that loud, i don't like exhaust tips, and it will support my new motor. an o2 bung would have to be welded into the collector of the header if you wanted to run this setup on your car. if you ever plan to lower your car, i do not recommend this setup for you. i have 5" of clearance at the lowest point (right under the transmission).

if your going to do a head swap, look into the new TrickFlow aluminum heads with the 58cc combustion chamber. p/n 30300005 from summit, they are $1005.95 but that's not economical for you right now i don't think. the stock 081 casting heads you have are really good with a home porting and bigger valves.

 

you are missing one little word there: each

just looked them up and: wow, 2k just for the heads... (probably a typo?)

 

Where did you get your pricing? Here are the ones at summitracing.com:
http://store.summitracing.com/defaul...=egnsearch.asp

 

here:
trick flow heads with 58cc

seems to be a fault there

 

i called them this past Saturday night and they are priced per pair. for the older style intake(90* center intake bolts), they are 969.95 and the new style intake(72* center intake bolts) they are 1005.95. don't think for a second that i would consider $2K for a 305. maybe a 427sbc, but not a 305. i wouldn't lead you astray when it comes to 305's. i want more fast 305's on the boards!

there is a misprint on the summit site, and the guy at Summit that i talked to said so as well.

 

guys, these heads are gonna revolutionize the 305's performance possibilities. i am planning on getting them as soon as the new tranny/converter goes in and my new draglites get here(bought some last night). specs on the heads:

aluminum (25lbs lighter EACH)
175cc intake runner
58cc combustion chamber
1.94/1.50 valve combo
screw in 3/8" studs and guide plates
plenty of meat for more porting down the road

Tim Burgess, tunedport335, i'm building a new motor (shhhh 335 shhhh) and i am coming after you guys and i am coming strong! motor will be carbed and n/a!

 

These heads sound similar to the aluminum L98 heads. we will see what mine runs this spring after it is tuned, i would guess my results will be similar to someone using the trick flow heads. it would be cool to see some flow numbers for those heads.

 

called trickflow, here are the flow numbers for p/n 3030005:

Lift Int. Exh.
.150 99 77
.200 126 102
.250 150 115
.300 175 128
.350 194 142
.400 213 153
.450 230 166
.500 240 170
.550 240 173
.600 240 178

 

3.73 gears
world tourqer 305 heads
thats what i had
my car ran like mid 13s with that and a few other mods til i blew up the motor and got a 350

 

Anyone knows if the trick flows have the egr port. Or is it the same as with the vette heads?

 

i'm gonna assume no by the pictures i have seen. may make an emissions legal swap difficult.

 

Based on the flow numbers i got from Chevy high performance database for the L98 heads those trickflow heads flow 40cfm more on the intake and about 10cfm more on the exhaust at .500 lift. that is based on a stock unported L98 head.

 

It's true, there isn't much difference.

I know the AFR heads are more expensive, but I really think that you will get a lot more performance out of them. The flow numbers leave trickflow in the dust.

Lift Intake cfm Exhaust cfm
.200 129 106
.300 195 156
.400 240 178
.500 255 190
.550 258 192
.600 260 194

 

I had a carbed 305 with about $600 in mods in my 5,000+ lbs van with a 3.08 rear and a 700r4 w/ 2,000 stall. All that it had done to it was heads I ported in my garage, Comp XE274H, edelbrock performer RPM intake, tuned Q-jet, recurved distributer, headers, and a low restriction dual exhaust system (still had cats). After playing around with some of my friends that owned mustangs and third gens they finally convinced me that I needed to run it at the track. Ran a 14.7 @ 98 with a 2.7 second 60' time. Imagine if I had traction and a decent gear. Then you have to think about how that 305 would have run in a F-body. Probably low 13s to high 12s easy. The G van had enough trap speed to run low 14s to high 13s so in a 1,200 lbs lighter car that has better gearing and traction with a TPI setup.


That engine dynod at 320 rwhp @ 5,700 and 300 rear wheel ft/lbs @ 4,200. The torque was table top flat from 2,700 to 6,000. The peak was 30 ft/lbs higher than torque at 2,700 and 6,000.


I miss the little 305 in the van because it would pull the van to about 130. The 350 can only go to about 115 or so becuase it just flat runs out of horsepower.

 

might a full 4" exhaust be a little overkill for an LB9? Shouldn't 3" be sufficient?

 

Yes, I wouldn't go over 3" exhaust, besides, you are just wasting cash on extra flow that you won't use. If you are going L98 one day, then you might want to do it and have it ready to go.

 

swap in a T5. remove weight, add headers, do the free mods, and buy some slicks.