Hey guys. I am thinking about upgrading to 1.6 rockers. I have a full bolt on L98 running 13.2's with 300 hp at the crank. Do you think this upgrade would be worth the money? What kind of performance gains would one see?

 

bump

 

What do rockers do anyway? I always hear people saying 1.6 to 1.....does it increase your lift duration? Does that mean it'll bump the int/exhaust on your cam?

 

Yeah I think thats what they do, but i think its something different.
Because people usually say use this cam and 1.6 rockers.... but why not just get a different cam....
so maybe it does something else?
but everyone says to do it whenever you mention wanting to get some hp out of your motor so cant hurt i guess.

 

Yes but I do not have enough money for a cam.

 

1.6 rockers just increases the lift of a cam around .33 from standard 1.5 rockers..... your stock 89 cam is .415/.430 with 1.6 rockers it will boost it up to .448/.463.. you might feel a little something.... there are different types of rockers... we have crappy stamped rockers... the are very innacurate and go from 1.39 to 1.52.... roller tips rockers are much better and stay at a constant lift..... roller tips also reduce friction.... so yes it does help.....

 

TPIS claims 15 hp

 

thats what they say.... but that is not true..... more like 5 or 6whp if that...... you have to remember that it also depends what your running.... they might be running no accesories with a much better intake with long tubes.... horsepower doesnt stack up like that... it all depends what you got and the right combination...

 

They prob meant 15 at the motor?

Right now I have a full bolt on L98. So maybe this mod is not worth the 134 dollars? This is a street car so I am only looking to add about 20 more horse power.

 

Maybe some after market pulleys would yeild better gains for the money. Mods are in sig. Only other things I can think of are the pulleys, rockers, and a 2800 stall which I cannot afford.

 

Personally I dont think underdrive pulleys are all they're cracked up to be, I didnt notice any difference nor did my et's drop any after installing mine. I think the 1.6's are worth the investment, My brothers old Lt1/auto car dropped about 3 tenths consistantly after we installed them with fresh springs. Since you have your L98 moving more air with your intake and exhaust mods there is no reason you shouldnt see gains in the 15hp range.

 

Thx for the responses. Do you know which ones I need? There are a bunch of different 1.6 sizes.

http://tpis.com/index.php?module=cat...ry=Rocker+Arms


700-301 Rockers, Aluminum 1.6 x 3/8........$124.00
700-303 Rockers, Aluminum 1.6 x 7/16........$124.00
700-311 Rockers, Steel 1.6 x 3/8........$134.50
700-313 Rockers, Steel 1.6 x 7/16........$155.00

Also do I need to order springs as well?

 

It's always good to put on some fresh valve springs, quality stock replacements will do fine. Also, since you would have the springs off anyway new valve seals would also be something to consider. Whatever rockers you go with need to be 3/8" stud and self-aligning.

 

Just out of curiosity... what cam do you currently have in it?
Is it a 300hp crate motor or have you done your own mods to get it to 300ponypower?

 

Those prices are for a set of 8. You would have to double the price. There are cheaper places to get your rockers from then TPIS.

 

yeah tpis has very high prices for everything...... i don't like them....

 

http://www.jegs.com/p/JEGS/831437/10002/-1

How do these look^^^

Maybe for the money under drive pulleys would be a better choice since both are probably worth ten or so horsepower.

 

Go to the website in my sig. Its a full bolt on L98 300 at the motor, 250 at the wheels.

 

underdrive pulleys are smaller diameter and weigh less, they purpose is to slow down accessories so it takes stress off the motor and give back stolen horsepower from stock accessories. your looking at about 15 horsepower from udnerdrive pulley and 6-7 from 1.6 roller rockers.

 

[QUOTE=roughskinjrz;4087107]underdrive pulleys are smaller diameter and weigh less, they purpose is to slow down accessories so it takes stress off the motor and give back stolen horsepower from stock accessories. your looking at about 15 horsepower from udnerdrive pulley and 6-7 from 1.6 roller rockers.[/QUOT

If I buy some can they work with the pre existing belts?

 

http://tpis.com/index.php?module=cat...ry=Pulley+Sets


I think I will get these.

 

I`m curious how`d you get 300hp at the crank with those mods.I dont see 60 hp worth of bolt ons IMO.I`m not trying to call you a liar,that just seems like alot of power for a bolt on L98.Especially with a hypertech chip.You 1/4 time seems fast too.Must have been a factory freek or something.I`ve got tpis lower manifold,slp runners and ported plenum about to go on when I`m done porting it.Cant wait to see what they do to my car.

You may have to pull the heads and have alittle work done to get the 1.6`s to fit correctly.

 

Most full bolt on l98 cars in here make around 240-250 rwp which equals 300-310 with a 20 percent loss.

 

I think I got 306 for my car w/20 percent loss. If you think about how restrictive the stock headers and exhaust are it makes sense. You can pick up 30 hp by getting good headers/cat back w/high flow cats, and another 25 with a ported intake manifold and runners. Theres 55 right there.



Here is a firebird modded by slp that made an extra 50 horse power with far less mods than my car.
https://www.thirdgen.org/slptpibuild-hpp-feb89


I also have my slips and dynos if you are interested.

 

Here it is. There guys in the thread below are making even better power than my car. Orr89 was hitting 13.8's with just cat back/headers, and 2800 stall!!



https://www.thirdgen.org/forums/tpi/...get-stock.html

 

I'd do both 1.6's plus the pulleys. lol. thats good for 20-25 whp. get the performance pulleys and not the high flow water ones. IMO i'd try to stay away from stamp rockers if for a few buck more the full roller rockers (less friction) would be the best gain in performance.

 

I think I'll just go with the pulleys. All I really wanna hit is a 12.9 and I think I can with pulleys and slicks.

 

id opt for pulleys over the rockers right now. slicks will help alot with your 60 foot to good luck let us know how it works.

 

I would go with the set of 1.6 or 1.65 roller rockers. Check out some other places then TPI's there always high on everything. Look in summit or jegs or sumthing. Youll get slightly better gas mileage out of them to, and a consist lift unlike our shitty stamped rockers. But its your choice, and with the mods that u have on your car you mite see a few tenths in the quarter with this upgrade.

 

 

Here's the ones I went with. I ran them before on another engine with underdrive pulleys and they definitely made a difference. I bought another set for my current project and will put them in as soon as I find the time. You will feel the difference, for sure.

http://www.jegs.com/i/Proform/778/66925C/10002/-1

http://store.summitracing.com/partde...C&autoview=sku

 

im feelin the pulleys just cuz I can install them in 30 mins haha

 

Sorry to be off topic.Once again.Not saying you`re full of bs.I`m aware its possible.As I`m aware of orr`s car and others who get deep 13`s or better with a stock head & cam L98.Usually hypertech chips are junk.Orrs car was tuned and tuned well when he got his best numbers.Stall,full exhaust,slicks I can see a 13.8.All I`m really saying is I cant wait to get my new intake and injecters in to see what it does.Ive never run the right size slicks on a full 1/8 or 1/4.I borrowed some slicks one time but they where 28" tall and killed my gear.Come to find out that the track I went to was not a full 1/8th.It was a 130' short.Figured something was wrong when I dialed a 7.1 my first run.I got 8.7 on crappy street tires on a full 1/8th.Just wonder if I can expect 30 hp with new ported intake with my current mods...or hopefully even better.I`m just not sure if its there.BTW,that 8.7 was with flowjunk headers and y pipe,2.73 gear and stock stall.

I do want to know what the underdrive pulleys do for you.20 hp?I`ve read alot of guys had problems with the car not charging or cooling like it should.I`d like to know for sure if such an easy bolt on makes any real differance without any adverse effects.I`ve almost bought some several times just to research it and read its not worth it.I`d like to be told differantly with some decent proof.

I would be interested to see or hear(read) what your timeslips were so I could compare to what mine where on that short track up to the last point they timed.Have to look at them again to find out what that was.

 

The funny thing is the hypertech makes better power than a TPIS chip I bought. My best mod was def going from 2.77 gears to 3.45's. Best run with the 2.77's was 13.7 on street tires I believe. I posted my dyno numbers on here awhile back, not sure exactly where. I had the car dynoed 3-4 times and the power ranged from 245rwh to 252whp, and 342rwt. Havent had the car dynoed yet with the new injecters so it may be a bit higher. When I had the gears installed the guy asked me if I had a cam in the car because he said it is very fast for what it is.



EDIT- 245whp w/TPIS chip 251whp w/Hypertech chip