I think it would be a good idea to put together a thread full of all the tips and tricks that people have used when swapping from TPI to LT1 intakes. People that have already done the swap and learned a little trick or could offer them up so that those of us getting ready to do it could learn from thier experience. This would be for things not found on John's site http://lt1intake.com
once completed maybe a Mod could make it a sticky so that we could get less repeat questions.

I did a search of over 5 pages of old posts. Here's what I found. Please feel free to add to these with anything that you have discovered when swapping yours.

1. You'll need to use a 94'-up LT1 intake due to the placement of the fuel rail crossover.
2. 89'up throttle bodies linkages are different and have some trouble clearing the coolant fittings.
(a resolution to this was unclear so anyone that could elaborate would be appreciated)
3. Most people have used a Felpro 1205 intake gasket with great success.
4. It appears that the Aeromotive AFPR will not clear the distributor.(The final answer to this one was not posted either. Anyone with the final answer please chime in)
5. The LT1 intake sits a few inches LOWER than the TPI one did and the TPI air intake tubing works but the path becomes less straight because it must travel down to the lower height of the LT1.
6. The EGR ports on stock TPI cast iron heads is not fully covered by the LT1 intake. Material can be added to the intake to remedy this. Most aftermarket heads either don't have the EGR passages or they are smaller and fully covered by the intake. L98 aluminum heads fall into the catagory of no EGR passages.
7. If you have an Automatic Trans you'll need to use the throttle cable bracket from a 93' LT1 because it is the only one that has provisions for the TV cable. (or fab up your own, of course)
8. Be sure to mount the remote T-stat housing below the level of the radiator cap so as to prevent air from being trapped in the housing.
9. some sensor wires need to be extended to reach thier new locations. Simply soldering a piece of wire is all it takes to do this. The ones that I know of that need to be extended are the MAT, coolant temp sensor and MAP(if equiped)(anyone that knows of another one please post it)


Everyone please contribute any other tips and tricks you have picked up.

Hodge

 

ADJUSTABLE FUEL PRESSURE REGULATOR:
The TPIS AFPR fits and clears the distributor with no problems. I recommend this one over all others because the hat can be positioned wherever you want it. There is another one out there that uses (what looks to be) the same hat as TPIS, but the clamp is perminant and you can not rotate the hat.
Cost: about $50 for hat alone (requires modification to the regulator to remove the existing hat), or about $100 for a new regulator and hat from TPIS


TRANSMISSION (TV) Cable (automatic transmission only):
It's been suggested that the 1993 Z28 cable be used for proper operation.
Cost: about $35

 

Here's the TPIS regulator on my intake.

 

10. The LT1 intake cannot be easily modified to fit Vortec heads. Lots of welding would be required.

(I had to add this one because someone always e-mails me on this daily)

 

11. You cannot re-use the stock TPI fuel rail or fuel pressure regulator. Only the LT1 style fuel rail can be used (1994-97).

 

any good sugestions as to what to use for the remote t-stat?

 

This pic was taken from John's website, http://www.lt1intake.com

Weiand - the part number is 7134P


All the info you need on hoses can be found on John's website.

 

10. The LT1 intake cannot be easily modified to fit Vortec heads. Lots of welding would be required.


What about the LT4 manifold, arent the ports raised the same height as the vortec ports? maybe a little port matching...?

 

The cost of getting a LT4 intake, which is only available new, makes that conversion cost prohibitive.
The intake alone is $200, then a fuel rail must be found....most people that have only the fuel rail for sale want alot of money for it.

 

Weiand part number 7134P is for the polished version. Part number 7134 is un-polished.

Offenhouser (sp?) offers one as well and has better availabity, that what I use now. Weiand (now Holley) is very slow to fill orders for their housing especially the polished version. Polishing is done by a thrid party and they broke their contract with Weiand.

 

The LT1 and LT4 use different fuel rails?
Why not a autozone replacement, or even a do it yourself fuel rail setup?

Cost isnt that much more...100 bucks?

I guess my question was, the ports on the LT4 match the vortec ports?

 

can you use the stock TPI throttle body?

 

I'd be shocked if Auto Zone sells fuel rails for the LT1/LT4 intake. GTA600, have you looked into this? Sounds bogus to me.

Those rails are well over $500 a set new from GM.

 

IM PISSED! i just bought a fuel rail and adj. FPR off ebay and this post just confirmed that the FPR will NOT work...just got the damn thing in the mail 2 days ago....oh well **** happens.

 

Yes you can use the stock throttle body.

 

How does the EGR blockoff effect emmisions testing? I have a 1988 305 TPI how much of a gain could I expect if I swap to an LT1 intake setup?

Thanks in advance
Mark

 

This is an excellent post and I vote that it goes "sticky".

 

What kind of increases are you guys seeing after the swap? On 350's, 305's whichever...are the cars able to rev higher because of the STR setup of the LT1? I noticed on the LT1intake.com site that the conversion requires the EGR be removed....has anyone in California done this swap and then passed Emmisions tests?

Ryan

 

EGR block off will only be a problem if you have a visual inspection under the hood. That's only certain states and I couldn't gues who that is, you will know if you live in a state that has visual inspections.

If you just have a sniffer inspection then you can still pass with custom chip tuning. Talk to Ed Wright for that.

 

I don't have dyno times. I do have before and after 1/4 mile times.

before 13.9x at 101 mph
after 13.4x at 105 mph

The "after' run was plagued with transmission trouble. In fact I crossed the
traps in 2nd gear/7200rpm because it wouldn't up-shift by itself to 3rd (governor trouble).
I really think I would have been even faster if not for that. I know it's an
excuse but the improvements are real. Judging by the mph improvement I
estimate a rear wheel HP increase of 40-50. That's 48-60 HP at the crank
with just an intake swap, no tuning.

 

Mine with LT1 intake, Brand New L98 shortblock, Crane Powermax 2032, edelbrock headers, catco high flow cat, and borla 3" cat-back passed PA emmisions with no tuning at all first try.

and actually I'v heard that the only time EGR does anything is when the car isnt warmed up. My emmisions test was done on a cold engine with no fuel aditives that help you pass.

 

what about hooking up an external egr?

 

Did you get the Aeromotive AFPR? I have one on mine and it works. it touches it but it fits. I was the one who made the post about thinking it would not fit but once installed it clears. BARELY

Ill get some pics of that, how i modifyed my 89+ throttle body linkage, and the intake tube (mine fits good). as soon as possible.

I had to extend the IAC, and TPS sensor connectors too.

 

So, does everyone agree that swapping an LT1 on my 89 305TPI 5spd (stock l98 cam) would net me 40HP at the rear wheels?
I'm skeptical.
I've heard of a few people around here swapping to LT1's and gaining everything in the top band of the RPM and losing down low.
I don't want to sacrifice low or mid range torque.

John, you should get some REAL dyno graphs posted with l98, lg4 and lb9 cars both in 5speed and auto configs. Give the intakes away if you have to. Once you got the proof out there, you won't be able to keep those lt1's on your shelf!

 

If you are good with a grinder you can get the cruise control linkage cable to sit correctly in the 93 LT1 throttle bracket, but you will have shim the linkage somewhat.

Use rtv on the distributor hold down bolt or you will have an oil leak.

 

Much of this is good stuff but lets try to keep the post limited to tips hints and tricks. If you have a questions like "is this good for me" or has anyone done it on a ***" please create a new post or do a search. all of those questions have been answered before. This post is designed to help those that are actually doing the conversion so that they can be sure to get all the right stuff to do the job right the first time.

Sorry for the rant.
As for the stickyness of the post. I'd like to redo the list above with the additional info contained in the rest of the post. Then that thread could be sticky'd and closed so that everything is all in one post. I'll give this post another couple of days to get all the info before I put it all together.

Sound good to everyone?

Hodge

 

Sounds good to me, Hodge. I haven't posted, but I'm pretty close to doing the LT1 intake swap (Hey John, I guess you're gonna have another customer coming your way soon). So far this has been a good thread to read, and to leave it sticky would be great.

I just have a question about the Throttle Body. I have an Edlebrock 52mm throttle body that I'm planning on re-using. Do you think I'd have any problems? Or is the problem easily rectified by some slight thinking and playing around?

thanks!

 

My Edelbrock 52MM throttle body fits fine.

 

Even with my nos throttle body plate I had interference with the coolant hose. Napa sells a shorter 1/2 heater hose fitting that gives you more clearance than the one John sends you.

 

That's another reason I am installing the coolant fittings in the rear now, aftermarket throttle bodies.

I will still honor a request for front coolant fittings. I think hiding them in the rear just looks better as well.

 

Way ahead of you Steve, I am getting an intake ready for a L98 customer that will do a before/after dyno graph for me.

Now if I can find a RELIABLE person to guarentee me a before/after dyno with a stock 305.......

 

Hey John, you just modified mine 3 weeks ago and put the coolant fittings on the front. If they work as well in the rear as the front, why? I didn't request that!

 

I don't really understand your question. You didn't request them front or rear. It was normal to install them in the front just like GM did with the thermostat housing on a TPI intake base. I just copied the GM design when I came up with converting the LT1 intake.

No where did I say my first design is the only design. I withhold the right to improve the design at anytime I see fit. I am the designer you know.