Samcro92

I want to upgrade my stock 85 vette. The main things I want to install are a new intake system, throttle body, runners, and hypertech chip. What are your thoughts?

oldalaskaman

1.2.&3, good, 4 bad

tunedport85inject

you said hypercrap chip... start with headers ...then heads and cam,then intake,if you don't go too radical with the cam you don't need retune it

Nathan Plemons

Correct me if I'm wrong, but isn't the stock TPI throttle body 48mm?

There's no horsepower to be had there, it's strictly eye candy. There is no way that engine is ever going to need a bigger TB if you are retaining any type of TPI system. Save the $300 for something else.

The Hypertech is also completely useless, what's that another $300? I've honestly never priced them, I know true custom tunes usually start there and go up.

Use the money you save on these parts to buy other stuff like a nice set of headers.

T. Wayne Nelson

If you want to build an L98 to run good, then, heads, intake, cam, headers, get rid of the MAF and get a standalone ECM speed density. Now you have a good start.....

tunedport85inject

you have a real gain with headers,another effective mod are 1.6 RR,but your 85 uses pressed in rocker studs and you can't bolt on RR on that cast iron heads...exhaust is important,you can buy headers from 400$.Your intake can be ported(base & plenum) and you have only to buy some good runners( AS&m for 400$)my wish list could be:

headers
heads+cam (185cc-195cc)
plenum&base ported (you can buy a miniram used when you find a good deal)
runners (SLP-TPIS-AS&M)this stuff is expensive
TB 58
torque converter 3000 rpm stall
stay with MAF (but 165 ECM 86-89 is faster than 870)some repinning to do + tune

this the way for performance...

RWH1290

Not sure what your goal is ?
1st-Cut out Air Filter cover lid and remove screen from MAF (Free Upgrades)
2nd-Headers-Long Tube
3rd- Hollow the cat-Open the exhaust. (depending on your states Insepction)
4th-Change gears in your rear. (Biggest SOTP change)
5th- Large mouth intake and runners..You can buy them or port your own.
Your stock chip is fine...all the Hyper chip does is advance timming(burns rich)and changes your fan on-off settings

Good set of heads and check your injectors..Early 85's Iron Heads(few options) Late 85's Alum(more options)

V's Vette

One input I have....I completely rebuilt my 89 and put the Lingenfelter Superram intake on. I would NEVER put it on again because of how frickin' hard it is to put on. If you want another intake, which I strongly recommend, look at the Miniram from TPIS. I gotta say that it is lots of fun to drive my car now that it doesn't run out of air at 4K+ rpm!!!

cumbercr

I upgraded the 350 in my 85 with a Super Ram, AFR heads, headers, mild cam and roller rockers. That engine made some great power and no tune was required. The Super Ram is really not that hard to install. There's plenty of tips and tricks on the forum.

But beware, once you feel the power, you'll want more. I've now moved up to a 396 with a more aggressive cam (221/230). Fortunately the heads, headers, throttle body and intake were a direct swap. But now I'm dealing with the tune. And this engine is smog legal. The Super Ram is the only aftermarket intake that meets CA smog.

John A. Marker

The 85 responds well to exhaust modifications.....free flowing cat or delete the cat. Are the mufflers stock with only one working exit pipe (there are two and one is blocked off)? Headers if they are legal in your state. Keep the TB and spend the money on March under drive pulleys. If you are going to keep the stock heads for now, then go with 1.5 and 1.6 roller rockers. The 1.5 goes on the intake and the 1.6 on the exhaust. This combination has worked well on the 85. Forget the Hypertech chip.

I would suggest that you read Vader86's web site. There is lots of good information there.

tunedport85inject

How do you put RR in a cast iron heads? (stamped rocker)
they run pressed in rockers studs and these bosses don't allow you to put guide plates...i think this heads are to be machined to put into RR,or ,you have to run self aligning rockers

cumbercr

I had Crane full roller rockers on my 85 with stock heads. I still have them in a box if the OP is interested.

tunedport85inject

Am i wrong?do you put RR in your cast iron heads as a bolt on kit?

Nathan Plemons

Does the TPI really respond well to headers if everything else is stock? I mean real dyno results, not just seat of your pants because the butt dyno is one heck of a liar.

I only ask because I've dyno'd an LT1 stone stock and then with headers and no other changes and saw virtually no change. It takes a cam to really take advantage of the headers. Now an L98 may have a much more restrictive exhaust to start with, but it also has a much more restrictive intake. Seems like they would offset.

I'm not saying it doesn't, just wondering if anybody has proven the gain?

cumbercr

There's a lot of difference in the stock exhaust manifolds on an LT1 versus an 85 L98. When you look at the collectors, the pipes are pinched almost in half. I don't know what Chevy was thinking when they designed them. They then feed into 2-1/4 Y pipe into a single cat. My butt doesn't lie that much.

Nathan Plemons

I bet you could get the same gain by swapping out the factory L98 exhaust for the factory LT1 exhaust. But that's a WHOLE lot of work when headers look WAY cooler and give you plenty of expansion room.

John A. Marker

tunedport85inject - In answer to your question....RR on stock iron heads? Yes you can without a problem. If you are using the stock cam the pressed in rocker arm studs will hold up to the roller rockers. You do not need guide plates with iron heads, they are needed for aluminum heads. Self aligning RR would be best. You do not need to machine the stock head. You WILL HAVE to take the stock valve covers and grind off the drip tabs on the underside of the covers. Do not attempt to break the tabs off. Cut them with a small cut off wheel and then grind them down with a die grinder.

Just remove the bolt that holds the stamped rocker in place and remove the stamped rocker. Replace with the roller rocker and the new lock nut. Adjust the rocker as you would any rocker arm.

From past Forum posts, members have indicated that you would get 10-15 HP installing RR's. I am sure that number is dependent on what heads you have and the ratio you install.

If you do some research you will find that the stamped rockers which are supposed to be a 1.5 ratio will vary from 1.4 up. Few will actually be the 1.5 ratio. Summit will sell split ratios of 1.5 and 1.6. You will find a few additional HP with this conversion and you will see your oil temp run 8-10 degrees cooler.

Nathan - The 85 does respond to exhaust modification. My 85 was running with the old L98 stock bottom end, AFR heads with the 1.5 & 1.6 RR and a few other bolt ons at 14.1 in the 1/4 mile. This was a consistent number. I removed the cat and built a straight through pipe for the track to replace the cat. At the same time I changed to March under drive pulleys. The car then ran 13.6 day in and out with only those two changes. I don't see the pulleys as being responsible for cutting off the .5 seconds at the track. Just allowing the exhaust to flow free without the cat had to be the major contributing factor.

tunedport85inject

Thanks john,i have a set of gold comp RR in my garage,i bought them one year ago,then thinking i was unable to fit into my cast iron i never attempt to put them into.Now i can try this way,they are 1.5 ratio,i would be better with 1.6,i know,but now i can start with my RR upgrade,thanks

John A. Marker

If you use the 1.5 and 1.6 combo, the 85 will idle much better. There will be NO ISSUES using 1.5 all the way around. How many miles on the engine? If there is a bunch...you might consider replacing the valve seals while you have the valve covers off. Forum suggestions were to use Felpro INTAKE seals for ALL valves.

Good luck.

John A. Marker

Samcro92 - sent you a Personal Message......