alterchristopher

Ok guys I just got done installing 90 modle tpi headers on my 93 lt1 only thing I added was some o2 bungs wich I welded to the collector on the longtube so if you want headers cheap thier you go

Longtube for ltx vette cost 500- 600 bucks
Tpi longtubes from headmen cost Me 170ish pluss 20 bucks for o2 bungs so 190ish for a set my only regret is I got 1&5/8 instead of the 1&3/4 but hope this helps

BADDUCK

How was the exhaust port match? How about plug clearance?

alterchristopher

Ports match up just don't go smaller than 1&5/8 plugs fit good but you can't get a socet on one I made this for my spark plugs
ttp://s61.photobucket.com/albums/h60/alterchristopher/corvette/?action=view&current=5eaf1110.jpg&evt=us er_media_share

MyFirst90coupe

Not sure what it is but here's the pic



I have been thinking of going the other way LT headers on L98

bill mcdonald

WTF is that, and are you in the right place?

MyFirst90coupe

That's the pic that alterchristopher tried to post. I have no idea WTF it is either.

edit- actually it looks like a wrench that he modified. hard to tell from the pic though.

cv67

Most 350s never need a 1-3/4 in primary anyway.

bill mcdonald

Ahh... I see the 5/8 stamp on it. Started to think he made a shifter out of a wrench and torch.

I had 1 5/8th hedmans on my AFR heads (l98). Seemed to do he job. I later picked up tpis 1 3/4 that I never installed. I have been on a bigger is better kick.

alterchristopher

That is my home made spark plug wrench to put spark plugs in with

GREGGPENN

Next time someone mounts early to late OR late to early headers and talks about the fit, port-match, etc..., the primary pictures that should be posted are the gasket sitting on the heads AND again against the headers.

Mostly because I don't trust what I can't see. Gotta be others like me too. (One person's "fit" is another person's port-match project too.)

Were those hedman's square or round-port headers?

alterchristopher

round i put the gasget against a set of stock heads thier was a little gasket over lap in the corners but this is normal in fact it over lapped the headers worse the lt1 are d-port's and the tpi are round
t
lt1

tpi

alterchristopher

also i should have new 1/4 mile times for you guy by sat first n/a then with 100 shot see if they help

STL94LT1

GREGGPENN

I always felt like headers were interchangeable as long as 1 3/4" were the topic. Last year, I cautioned another member for putting Hedman 1 5/8" L98 headers on AFR heads. That's because the AFR and LT exhaust port config are much more similar.

First, that member said "no problem"...they fit. IIRC, that statement was later modified to say a bit of porting was required to avoid "covering the ports". Without pics, the feedback was purely subjective. Not something the avg builder would consider definitive -- though hopeful.

I would take that one step further and say the budget-minded builder is probably more likely to make things work...or accept small concessions with a more open mind. Or...maybe ALL L98/LT headers are virtually interchangeable as described. (Hmmmmmm....I wonder why Summit and other websites don't list them that way?????)

Anyway, here's the issue I see. I've tried to describe it in words before but the two pics above let me illustrate it better. LTx exhaust ports are considered higher. Without measuring/comparing, I don't know if that mean taller or it's moved up in the head. Look at how much of each port is above the red line in my comparison....(Notice how more is above the LT head [top] vs the L98 head [bottom].)



My concern has always been that, if a given 1 5/8" header (especially circle/oval port) is designed to fit exactly around the perimeter of a given exhaust port, then moving said port up/down (in relation to the bolt-line) would throw off the match. OTOH, if it's a bit bigger -- like I'd expect a 1 3/4" header to be -- then there shouldn't be an issue.

The yellow circles represent how close a 1 5/8" header might be. OTOH, maybe the L98 port is smaller overall. Certainly, that would explain one of the reasons LT heads are reported with better flow.

alterchristopher

i agree with you i didnt and dont want to give out the wrong info to the point that the headers have been on my car for a week now just to make sure that they didt throw codes i also did alot of asking on ltxtech befor i bought them here are the rules the fbody guys go buy when swaping in lt1 into 3 gens

Thirdgen(82-92) f-body lt1 swaps use sbc(tpi) headers, these are the guidelines those swaps go by for headers:
1. Headers must have 1 5/8" primaries or larger
2. You drill an extra hole for an O2 bung to be welded in for the 2nd O2 sensor. You can get an O2 bung from summitracing.com
i had to drill both

i was also told this
TPI has 58cc and Lt1 has 54cc

now even with that i just went out their and mesered agian it all seems to line up really well, wish i would have taken a pic of the gasket on the head for you i did line it up first with bolts looked good i will say this i bought the 1 5/8 by mistake i wanted 1 3/4 and will be going to them soon (dont by parts at 4 am afters working a 12 hour day shift) when i do swap them i will take pics of everything for you guys utill then i will say go with 1 3/4 to be sure
will see if track times and or mph improve thats the real deciding factor for me weath they are worth it

and as far as summit i just figured that they were listed diffrent because of the o2 bungs

MyFirst90coupe

Could the be listed differently due to the smog connections

alterchristopher

That as well I got rid of me egr and air pump stuff when I installed the long tubes

GREGGPENN

I believe 58cc is correct, but I thought LT1 exh ports were 62cc.

Good point about the smog connections OTOH, plain (race) headers seem to have the same divisions.

Glad everything looks good to you...Pictures would be good sometime (for others), but don't feel obligated. If you're happy, that's the important thing. And, depending on the rest of your mods, you may not need 1 3/4" tubes for the duration.

alterchristopher

That all depends on how much I pic up in the 1/4 wether or not I'm happy the but dyno sure feels better but that can lie 1/4 Mile slip don't I will keep you guys posted

whitebrow

Here are some flange drawings with dimensions - might be useful:

Gen1 Square Port 1-5/8: http://www.schoenfeldheaders.com/FlangeDIM/01101dim.jpg
Gen1 D Port 1-3/4: http://www.schoenfeldheaders.com/FlangeDIM/01111dim.jpg

LTx D Port 1-5/8: http://www.schoenfeldheaders.com/FlangeDIM/0103dim.jpg
LTx D Port 1-3/4: http://www.schoenfeldheaders.com/FlangeDIM/0104dim.jpg

Course this doesn't address the height they're mounted at, but it does look like LT on SBC might block some of the bottom of the port and SBC on LT might block some at the top.