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I have these on my 80 cutlass 455 .The fit was great with no issues.they are well built and sound good .Not sure how the performance would compare to factory manifold or long tube headers. I am happy with them though
I have these on my 80 cutlass 455 .The fit was great with no issues.they are well built and sound good .Not sure how the performance would compare to factory manifold or long tube headers. I am happy with them though
No dyno tests have been performed on a 455, but there was a test on a W-31 built to pure stock specs for the Pure Stock drags. 12 to 1 compression, light weight pistons, etc. Initial HP/TQ with the Thornton 350JR manifolds (essentially a W-30 manifold cast to fit a SBO) showed 475HP & 526 lbft. A switch to shorty headers showed a jump to 500.7 HP and 540.9 lbft. A switch to long tube headers showed an increase of 11 HP over the shortys. Torque figures were not given for the long tube test. I know it's not exactly apples to apples, but it does give a general ballpark if your engine is in the 475HP range. Obviously your gains will go up or down depending on your initial HP level. Hope this helps. http://classicmusclecarexhaust.com/p...bile-headers-1
They look MUCH better than their first design!!! We just bought a set of the new ones for small-blocks for a W31 clone we're building. The new style looks really nice, well made, don't really care about the performance aspects, it was them or the cast iron Thornton 350 JR iron manifolds. That original log design looked horrible & probably performed way less than a set of W-Z manifolds !
No dyno tests have been performed on a 455, but there was a test on a W-31 built to pure stock specs for the Pure Stock drags. 12 to 1 compression, light weight pistons, etc. Initial HP/TQ with the Thornton 350JR manifolds (essentially a W-30 manifold cast to fit a SBO) showed 475HP & 526 lbft. A switch to shorty headers showed a jump to 500.7 HP and 540.9 lbft. A switch to long tube headers showed an increase of 11 HP over the shortys. Torque figures were not given for the long tube test. I know it's not exactly apples to apples, but it does give a general ballpark if your engine is in the 475HP range. Obviously your gains will go up or down depending on your initial HP level. Hope this helps. http://classicmusclecarexhaust.com/p...bile-headers-1
interesting !thanks for posting ive not seen theses numbers .
interesting !thanks for posting ive not seen theses numbers .
Troy Thornton has not had the opportunity to dyno any of his exhaust products yet, so these figures that he got from a customers' testing were very enlightening indeed. The line of SBO, BBO, and SBC headers that he's developed are first rate. These headers are a brilliant concept for street driven cars- none of the fitment and ground clearance issues with only a minimal HP loss vs. long tube headers. Just use a BBO or BBC 2.5" downtube from Pypes and you're set. I have a set of his SBC headers on my Chevelle and they're awesome. I have P/S and A/C, and they fit like a glove. As stated in a previous post, the current version of BBO headers are a much improved evolution from the first set. Troy's products as well as his restorations are at the highest level, and the fact that he is such a nice guy (and his entire family too) make him a rare exception and a pleasure to deal with. I have become a distributor for his exhaust products and I sell them on my website, but honestly I just like go to his shop, hang out and have a few laughs. Not many places/people you can do that with these days.
Hows it going Phil, iam not sure i was going to see what replies i would get on these, I have the W Z manifolds on the car now, Boy just looking at these looks like they would have some kind of a positive gain even just on the weight alone, one more thing were going to do a cam shaft change over this spring ! are you getting your olds ready to roll ?? john...
I'm good pal, locked in as of 8pm. The city is on pause, till whenever...
I think you may get a boost from the shorty's, I think the long tubes may work out even better. But I also get the headaches that come with long-tube / full length headers. Swapping that cam to something more aggressive should be the icing on the cake. Once you tune the car to the new go package I'm thinking its gonna be lights out.
With regards to my 69 yes and no. Got some things done last fall including a timing chain replacement. Only got 1 session in at the track with almost no gain across the board. Car still needs some kinks sorted out, that I was looking forward to getting done now. Alas NY/NJ have lock-downs going on due to the Virus, so looks like no possible track time in the near future. I'd rather not go in the summer, she does not like the heat performance wise. So maybe in the fall God willing.
Phil, keep me posted and the rest of the gang on how your doing on the 69 car !!, ill keep you posted also its going to be a while yet for me also, john..
Troy Thornton has not had the opportunity to dyno any of his exhaust products yet, so these figures that he got from a customers' testing were very enlightening indeed. The line of SBO, BBO, and SBC headers that he's developed are first rate. These headers are a brilliant concept for street driven cars- none of the fitment and ground clearance issues with only a minimal HP loss vs. long tube headers. Just use a BBO or BBC 2.5" downtube from Pypes and you're set. I have a set of his SBC headers on my Chevelle and they're awesome. I have P/S and A/C, and they fit like a glove. As stated in a previous post, the current version of BBO headers are a much improved evolution from the first set. Troy's products as well as his restorations are at the highest level, and the fact that he is such a nice guy (and his entire family too) make him a rare exception and a pleasure to deal with. I have become a distributor for his exhaust products and I sell them on my website, but honestly I just like go to his shop, hang out and have a few laughs. Not many places/people you can do that with these days.
Thank you for posting all the info.
I'm a believer in Thornton products.
I understand the shorties were made to give us Olds people options and not to compete with long tube headers.
I bought a set to use on my 455 build,in my case they are just what the Dr ordered. They give me a nice performance non stock look without the hassles of long tube headers and according to the info you provided are just what I was hoping...the shorties are a nice compromise between manifolds and long tube headers for guys like me who are not after every last horsepower.
Thank you for posting all the info.
I'm a believer in Thornton products.
I understand the shorties were made to give us Olds people options and not to compete with long tube headers.
I bought a set to use on my 455 build,in my case they are just what the Dr ordered. They give me a nice performance non stock look without the hassles of long tube headers and according to the info you provided are just what I was hoping...the shorties are a nice compromise between manifolds and long tube headers for guys like me who are not after every last horsepower.
Explain hassles with long tube headers with a 455? What year of car are you talking about 70/71/72?
While they are nice and pretty, you won't see much of a gain over the W/Z manifolds. They don't have the scavenging effect that long tubes have. I would just keep the manifolds.
While they are nice and pretty, you won't see much of a gain over the W/Z manifolds. They don't have the scavenging effect that long tubes have. I would just keep the manifolds.
yeah and getting every last horse power requires more than long tube headers wouldn't you agree? On side note if I wanted shorty headers these look like a good choice.
Last edited by wr1970; March 24th, 2020 at 02:30 PM.
Explain hassles with long tube headers with a 455? What year of car are you talking about 70/71/72?
I would say hassles would be subject to different opinions,to me these are the hassles.
I'm referring to my 71.
I don't want to spend big money for a set of ARH and still have some of the following to deal with.
I know gaskets have come a long way but remember the blown out gaskets? Cheaper headers,rust,have fit issues,can require moving the proportioning valve and needing a mini starter.
A big issue with me is losing ground clearance,don't want to loose any.
Back to the shorties,they fit my agenda perfect!
A street engine that I'm not searching for every last hp,I keep my ground clearance,probably less then half the cost of quality headers,gives me the non stock look with none of the hassles.
I would say hassles would be subject to different opinions,to me these are the hassles.
I'm referring to my 71.
I don't want to spend big money for a set of ARH and still have some of the following to deal with.
I know gaskets have come a long way but remember the blown out gaskets? Cheaper headers,rust,have fit issues,can require moving the proportioning valve and needing a mini starter.
A big issue with me is losing ground clearance,don't want to loose any.
Back to the shorties,they fit my agenda perfect!
A street engine that I'm not searching for every last hp,I keep my ground clearance,probably less then half the cost of quality headers,gives me the non stock look with none of the hassles.
Dude non stock look is the mini starter that is way better than stock. Hooker makes a very good in the frame header. I guess you never heard of using sealant instead of a paper gasket for headers. That being said I respect your choice it is your car.
For me they are in a 1980 cutlass the only decent options I had with long tubes were hookers that wrapped around the frame (at the time about 700 dollars )or arh inside the frame ( which I’ve heard good things about ) but! 1400 dollars .I guess most people have more patience than I do because I’ve never not had issues installing headers .These Thornton’s and factory manifolds are by far the easiest install .Im not sure if they are even considered a shortie header , but they are well built and work good for me. if someone said to me here’s 10 hp I would take it.
just installed mine today, thorton headers are very high in quality and the fit is amazing, order the pypes down pipes also. cant get any easier. high quality its worth the money. I have spent a lot more on a l
ess quality header. 67 cutlass.
just installed mine today, thorton headers are very high in quality and the fit is amazing, order the pypes down pipes also. cant get any easier. high quality its worth the money. I have spent a lot more on a l
ess quality header. 67 cutlass.
Looks clean! What mufflers did you use? How do they sound?
I realize this is an older thread but this topic comes up periodically so I like to add my 2 cents whenever possible. My '69 442 with a 'slightly' modified 400G had the original W/Z manifolds on it and after the engine upgrades, my fear was that I was choking the engine somewhat since the intake side was breathing better than stock (Performer intake & aluminum heads) but the exhaust side was still utilizing the manifolds. Granted the W/Z manifolds are good with divided runners, the engine would certainly take advantage of long tube headers.
The only set I really considered putting on the car were ARH since the rest of the exhaust is stainless and I wanted to keep the system 100% stainless and the quality of the ARH parts look to be top notch. I was having a hard time coughing up the money for those so ran the W/Z manifolds for a year or so. When I saw these Thornton short tubes, I decided to give them a try. Here are my observations:
* YES, I understand the engine's breathing/cylinder evacuation would be better with the long tube headers.
* The Thornton manifolds are of a very high quality. I went with the unpolished versions and found the tube bends, welds, flanges, collectors, installation and fit to be designed and built very well.
* Installation was pretty straightforward. Had to remove the oil filter and die cast filter bracket on the passenger side and getting the rear-most bolt in that side was a royal PITA due to the A/C box. Dropped the starter on the driver's side but that was it.
* I had 2.5" Pypes stainless downpipes on it with the W/Z manifolds and they fit perfectly with the Thornton's. No interference or issues.
* The original W/Z manifolds had the typical pitting on the pipe connections and mine also had deterioration of the center divider on both sides. This allowed for some amount of undesired gas 'sharing' between the center ports. The Thornton parts fixed both issues.
* Did I see a performance difference after the swap? Honestly, I did not. If you're simply chasing performance, go with the long tubes and don't look back. For me, this was a great compromise over the W/Z manifolds and I'm not at all sorry I spent the money on them.
Hope this info helps others.
While they are nice and pretty, you won't see much of a gain over the W/Z manifolds. They don't have the scavenging effect that long tubes have. I would just keep the manifolds.
I know this is an older thread but this is what I was looking for. Trying to justify dumping my W Z manifolds for the Thornton shorties. I was worried about my in process 455 build (should be in the 450 HP range) being too restricted with the W Z's even though from the manifold back I'm going 2.5 inch. It doesn't seem like much extra power switching to the Thornton shorties so I guess I'll keep the W Z's.
No dyno tests have been performed on a 455, but there was a test on a W-31 built to pure stock specs for the Pure Stock drags. 12 to 1 compression, light weight pistons, etc. Initial HP/TQ with the Thornton 350JR manifolds (essentially a W-30 manifold cast to fit a SBO) showed 475HP & 526 lbft. A switch to shorty headers showed a jump to 500.7 HP and 540.9 lbft. A switch to long tube headers showed an increase of 11 HP over the shortys. Torque figures were not given for the long tube test. I know it's not exactly apples to apples, but it does give a general ballpark if your engine is in the 475HP range. Obviously your gains will go up or down depending on your initial HP level. Hope this helps. http://classicmusclecarexhaust.com/p/thornton-
big-block-oldsmobile-headers-1
this link isn’t working. Does anyone know where it can be found?
Too bad the link is dead. Unless a down pipe is a true 2.5" like the Ram Air Restorations and not the necked down Pypes down pipes, there won't be much gain. Thornton should get a true 2.5" stainless down pipe made as none exist, that I have seen for Olds. Most magazine test for other makes show about 15 to 20 HP/TQ over manifolds and basic full length headers about 10 to 15 HP/TQ over shorties. This is the only test I have ever seen for any Olds shorties. My current exhaust has nearly fried, at least 10 year old Sanderson shorties with custom 2.5" down pipes. I had a brand new set of Sanderson shorty headers, I had sent to Mark Remmel to test on the dyno. I have bought 3 other sets of these headers, including one uncoated set. He suggested the uncoated for dyno duty and he would send them to be coated for me after. I had them dropped shipped to Florida. The welds were by far the worst of any of the 4 sets, looks like I did them😳 or a small child in the third world. I was given the BS response, they are supposed to be rough and need finish work before they get coated, apparently🤨. I hope Mark does test them, they need grind time for it to be fair. I just bought a set of the Chinese full stainless to put on the 358 in the 70S, it has a dual hump crossmember and good ground clearance. They are a really nice header with way better welds than the Sanderson for $300 Canadian shipped, half the price of the Sanderson or the Thornton shorties. I am looking to purchase another 88 to 95 GMC/Chebby 4x4 to Olds power and shorty headers or manifolds are the only option. Hopefully Mark does test them. This is the worst side and the angled collectors look like they were beat with hammer, not using them.
I was thinking it was a link about the engine dyno test?
guess not
The only dyno test on Thornton headers (that I know of) was on a 350 refered to in post #7. It was a modified W31 making 475hp with Thornton 350jr manifolds, and the headers were worth another 25hp. I'd be real curious to see if those results would be similar on a 455.
The only dyno test on Thornton headers (that I know of) was on a 350 refered to in post #7. It was a modified W31 making 475hp with Thornton 350jr manifolds, and the headers were worth another 25hp. I'd be real curious to see if those results would be similar on a 455.
I would assume the results would be very similar for the 455, losing about 25 HP by using manifolds over headers. Still unsure, if I want to go the shortie route. I could always change it down the road.
I would assume the results would be very similar for the 455, losing about 25 HP by using manifolds over headers. Still unsure, if I want to go the shortie route. I could always change it down the road.
As far as long tubes go, these BBO headers from American Racing Headers are generally considered the cream of the crop for quality and fitment. Definitely not cheap, but you are getting what you pay for. ARH Big Block Olds
March 21st, 2020, 03:20 AM
