mcm95403

Hi Guys,
I had some time this evening, so I took lots of pics of the LT-1 manifolds and included comparison pics with the L-98 headers. All the info is here:

http://www.marcmedina.com/LT1manifolds.html

And here are a few teaser pics:







Like those shiny pieces? Those are to build the air injection tubes to keep all the smog equipment in place. Two are (VERY difficult to find) 5/8" inverted flare fittings (7/8-18 thread with a 5/8" hole for the tube) and the two longer ones are 1/2" pipe (to go into the stock check valves) with a machined seat for a 5/8" o.d. tube. I'm going to drill out the center of those a little bit just to make sure I have enough air flow. All I have to do now is source the tube locally, bend it to fit, flare one end and have the other end welded.

For full detailed check out the link to my site. Once the tubes are done I'll clean up the manifolds and figure out a time to do the swap.

I know people will be asking, so I'll pre-empt the questions. Yes, I would like to do before and after dyno sessions to see what happens. Since I was laid off again 2 weeks ago there's nothing in the budget for that right now. I'd also like to replace my y-pipe and main cat, and if I do that I'd want to do it before the manifold swap so that I can get correct results for the manifolds alone. Again, this is another $500 that I don't currently have, so that is a further delay in the installation. Maybe I can get one of the local guys to set me up with a dyno session or two in the interest of pubilc knowledge

frank carlson

I read your post and would like to upgrade my 1988 L98 with the Street Ram and the LT-1 manifolds. I am also in Ca so I would need to be compliant with smog laws. What do you think your horsepower increase was from the street ram install? Also, what HP increase are you expecting from the LT-1 manifolds ?. Are the LT-1 manifolds readily available on the net or parts outlets? Thanks for your comments?

cv67

slickfx3 did this to his in ca came out real clean.

Truly "legit" who knows but its all there doubt the tech would bother it.
IF they did you could take it to the state ref who I could almost guarantee would pass it. All they care about is everythings on there;L98 manifolds are NLA... Its factory stuff....Id go for it those L98 manifolds are terrible in comparison. Been down that road before. They are more lenient than youd think. (refs)
Where in Ca?

mcm95403

Hi Frank,
The Street Ram felt like it improved things across the board. The more you rev it, the more you feel the difference. I didn't do a before and after measurement, so I can't give you any numbers, just seat of the pants feel.

As for the LT-1 manifolds - I really don't know what to expect other than (hopefully) significantly better mid-range and upper RPM. The stock headers are SO bad that anything will be an improvement. Obviously, they won't be as good as real 4 into 1 headers, but they will be a lot better than what is on there. Hopefully next week I can work on getting the air injection tubes bent to shape. It would be great to see 15hp at the wheels in the top end, but I just don't know. If I can replace the cats and get a dyno run in before doing the manifolds and then again afterwards, we should have some good documentation.

If nothing else, I'm sure they will help later down the road when it comes time to change the cam and/or heads.

856SPEED

are the stock LT1 exhaust manifolds that much better than stock L98 manifolds to see any signifcant RWHP gain??

just asking, don't know....

TA

What's a street ram?

mcm95403

That's the Accel high-flow base, big tube runners and ported plenum. Along with the 58mm Accel TB, it's the only other smog-legal intake for the TPI cars besides the Accel Super Ram.







Gratuitous logo shot

mcm95403

In my opinion, yes the LT-1 manifolds are far better. As I said, I hope to do before and after dyno runs to get real numbers.

PLRX

Are you having issues with those Accel fuel injectors? I bought a set years ago and they got the idle all out of whack. I sent them back right away.

Ordered FIC and never looked back.

ch@0s

I ended up switching to LT1 exhaust when I had fastburn heads.The fastburns have a D port design and even my Headman header ports were smaller than the LT1 manifold ports. Not to mention it is dual 2.75 compared to single 2.25. IMO they were a great improvement. Changing over was not hard at all and I picked up the stock cat-back for $100. I'm still running the Stock LT1 exhaust into 98 vette manifolds on my LS swap and they sound great.
I have it documented in my exhaust comparison thread.
http://forums.corvetteforum.com/c4-t...-videos-4.html

mcm95403

I have a set of Bosch III's from FIC that are working great. The first set I got was Yellow and they weren't working well, but John sent me a replacement set of black ones that are great. One phone call was all it took and I had the replacements in 3 days. I can't say enough good things about FIC and John!

856SPEED

interesting posts.....thanks for the info!

leesvet

Is there a particular yr LT ex manifold that fits the L98? or is it pretty much any/all LT ex will fit?

I'm thinking of doing this to maintain the stock "look" but I do not need to worry about the AIR system...in my state my car is classic now so the inspectors do not even raise the hood now.

ch@0s

They are all the same.. the 96 had a cross over but still the same. If you look at the link I posted you will see how easy it is to do. If you dont need cats your lucky.

mcm95403

The great part is that they look like they will bolt right up to the stock y-pipe, so you can keep your existing cats or whatever you have there and just bolt them in. If you don't need the smog stuff to work, all you'll need is a couple of 5/8 inverted flare plugs (the threads are actually 7/8" - 18) and an EGR blockoff plate. For those who need to keep the smog stuff working, stay tuned and I'll post more when I have the air tubes finished and decide the best way to route the EGR.

zach89

where can yo find them street ram intakes? i'm not worried about smog or anything like that because i'm in south dakota and they dont have emissions or anything here, just really curious where to pick up some good performance parts $1000 and under or somewhere around there?

mcm95403

I found it using www.searchtempest.com to search all of craigslist nationwide. They're not easy to find, but you can find Super Rams that way.

ch@0s

There are way more options if you are looking for an intake and don't have to worry about emissions.
HSR
Superram
miniram
proflo
FIRST and more
do a search before you decide.

Coupe89

In California you need the EO (Executive Order) sticker.
I know that the Superram has it.