LT header dyno result?
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Joined: Sep 2009
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LT header dyno result?
Ok I am researching LT headers (brands) for my car and have a question for you guys who know. On a bone stock 1998 C5 I came across a dyno sheet before and after results does this seem correct (avg gains or kind of high?) for just LTs w/tune on a stock 98 C5?
1998 bone stock C5 dyno results w/headers & tune.
31 RWHP increase
38 Tq increase
Also the under the curve power was very (from 2500^) good all the way up!
1998 bone stock C5 dyno results w/headers & tune.
31 RWHP increase
38 Tq increase
Also the under the curve power was very (from 2500^) good all the way up!
Last edited by TR97C5; Dec 20, 2009 at 06:34 PM.
Tech Contributor
Joined: Dec 1999
Posts: 32,910
Likes: 2,402
From: Anthony TX
CI 6,7,8,9,11 Vet
St. Jude Donor '08
Sounds very reasonable. 25-35 HP gain is reasonable. You going to need a tune to get all the power out of your MOD. In that same statement,,,it would be very wise to install all the MODs that you can afford at once and then get your tune. Here are someMODs that very worth wild with headers:
Coolant bypass
Ported Throttle Body
VARARAM
178 Deg Thermostat
High flow CATs
ZO6 Ti mufflers or After Market mufflers.
Professional TUNE. GET one after all the mods you can afford.
Without a tune, your LTFT will be positive and your fuel economy and AFR's will be out of whack costing you HP and Fuel mileage,
BEEN THERE,,,,,,,,,,,,,,,,,,,,,Experienced that!
BC
Coolant bypass
Ported Throttle Body
VARARAM
178 Deg Thermostat
High flow CATs
ZO6 Ti mufflers or After Market mufflers.
Professional TUNE. GET one after all the mods you can afford.
Without a tune, your LTFT will be positive and your fuel economy and AFR's will be out of whack costing you HP and Fuel mileage,
BEEN THERE,,,,,,,,,,,,,,,,,,,,,Experienced that!
BC
Thread Starter
Instructor
Joined: Sep 2009
Posts: 196
Likes: 3
Sounds very reasonable. 25-35 HP gain is reasonable. You going to need a tune to get all the power out of your MOD. In that same statement,,,it would be very wise to install all the MODs that you can afford at once and then get your tune. Here are someMODs that very worth wild with headers:
Coolant bypass
Ported Throttle Body
VARARAM
178 Deg Thermostat
High flow CATs
ZO6 Ti mufflers or After Market mufflers.
Professional TUNE. GET one after all the mods you can afford.
Without a tune, your LTFT will be positive and your fuel economy and AFR's will be out of whack costing you HP and Fuel mileage,
BEEN THERE,,,,,,,,,,,,,,,,,,,,,Experienced that!
BC
Coolant bypass
Ported Throttle Body
VARARAM
178 Deg Thermostat
High flow CATs
ZO6 Ti mufflers or After Market mufflers.
Professional TUNE. GET one after all the mods you can afford.
Without a tune, your LTFT will be positive and your fuel economy and AFR's will be out of whack costing you HP and Fuel mileage,
BEEN THERE,,,,,,,,,,,,,,,,,,,,,Experienced that!
BC
Thanks for the response and advice Bill. I thought those numbers might be kind high as I tired to find a another dyno sheet to back up those numbers per those headers/brand but couldn’t find another dyno sheet for that brand of header and stock C5 combo. But your saying those numbers look possible so sounds good to me then. Another question for you I was thinking of doing the headers (w/HF cats) now and a cam later this year. So I think your saying without a tune my AFR with be off or rich(?) due to positive reading and the LT fuel trims with the LT’s so power will be down a little from the full increase normally w/LT's tuned if I got that right .
I have a tune from ECS now I believe ECS said if I remember correctly will update my tune for just the cost of mailing in my PCM . Do you think or know if ECS can update my current tune for headers with out any data logging from me (no software or wb) and if they could do you think it would be pretty (90-95%) close? If not or they can't in your opinion is it all right /safe motor wise to drive the car with the LTs till I get the cam in and then get a dyno tune which could be months later?
TIA
Last edited by TR97C5; Dec 22, 2009 at 04:15 PM.
Drifting
Joined: Nov 2006
Posts: 1,682
Likes: 2
From: Plano Texas
St. Jude Donor '08
Ok I am researching LT headers (brands) for my car and have a question for you guys who know. On a bone stock 1998 C5 I came across a dyno sheet before and after results does this seem correct (avg gains or kind of high?) for just LTs w/tune on a stock 98 C5?
1998 bone stock C5 dyno results w/headers & tune.
31 RWHP increase
38 Tq increase
Also the under the curve power was very (from 2500^) good all the way up!
1998 bone stock C5 dyno results w/headers & tune.
31 RWHP increase
38 Tq increase
Also the under the curve power was very (from 2500^) good all the way up!
If you haven't had a tune, then those numbers could very well be correct. From my initial tune from stock (only had air intake & cat back exhaust), I gained 39hp and 27 ft/lb torque. Here is the dyno from that:
When I added lg street headers, headers themselves added on 25hp and 19 ft/lb torque. Here is the dyno for the header install:
So from stock baseline dyno, with headers and tune, I added 64hp and 46 ft/lb torque
Last edited by RLYSLO; Dec 20, 2009 at 09:01 PM.
Thread Starter
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Joined: Sep 2009
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still asleep thanks for posting those dyno sheets ^^^ always like to look at this data. Wow all I can say is that is a very BIG increase from just air intake, cat back & tune at 39rwhp & 27 ft/lb if I am reading that right!
I would of really been interested in seeing a dyno without CB & AI with just your LG streets on your bone stock C5 to see what the results would have been.
Thanks for posting those dyno sheets!
I would of really been interested in seeing a dyno without CB & AI with just your LG streets on your bone stock C5 to see what the results would have been.
Thanks for posting those dyno sheets!
Last edited by TR97C5; Dec 20, 2009 at 09:27 PM.
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BC disregard my questions on tune with headers I talk to ECS today they can update my tune no problem (great service ECS! 
) for headers said it would be 95-98% close. So I just have to ship the PCM to them. So I am good to go with that I'll just do a dyno tune when I get the cam in.
BTW here is that dyno sheet of the bone stock MN6 C5 before and after (+31rwhp-+38Ft lbs) thought I'd post it. It still seems kind of high to me imo but seems on some cars might be possible. I have decided go with these LG street headers with high flow cats as I found a good deal from a vendor (on sale) on a new set so bang for buck looks decent w/HF cats..
If anyone has any dyno sheets stock or mostly stock with just headers before and after if you could post them I'd be interested in seeing different results w/ under the curve power.
) for headers said it would be 95-98% close. So I just have to ship the PCM to them. So I am good to go with that I'll just do a dyno tune when I get the cam in.BTW here is that dyno sheet of the bone stock MN6 C5 before and after (+31rwhp-+38Ft lbs) thought I'd post it. It still seems kind of high to me imo but seems on some cars might be possible. I have decided go with these LG street headers with high flow cats as I found a good deal from a vendor (on sale) on a new set so bang for buck looks decent w/HF cats..
If anyone has any dyno sheets stock or mostly stock with just headers before and after if you could post them I'd be interested in seeing different results w/ under the curve power.
Last edited by TR97C5; Dec 21, 2009 at 04:46 PM.
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Safety Car
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From: Monticello MN
Ed
Last edited by C5XTASY; Dec 22, 2009 at 11:12 AM.
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Doug just wanted to add the service and support after the sale has been excellent from ECS. First awhile back you answering my questions on removing the MAFS screen and offering to update my ECS tune for that (if I could data log) by just sending in the PCM and now also offering to update my tune for headers which made my day. All I can say is I am happy I choose you guy’s (ECS) to go with on a mail order tune you guys have been great!
Thanks!
Happy Holidays
Last edited by TR97C5; Dec 22, 2009 at 04:16 PM.
