Log manifold how much power? | Open/closed wastegate discussion
 

I've searched this topic for the past few hours and didn't find exactly what I was looking for so I wanted to ask you all with first hand experience some question's...

Recently how much power have you ever seen a b-series engine make with a ss log manifold?

I've read the open dumptube vs recirculated threads and no one posted proof or said they have seen first hand someone gain power from using a recirculated dump and then opening it up..

I'm in a pickle here because when i ordered my turbo setup i initially was only looking to make 300-350whp... now that I have sleeved my block (84mm Type R, 9:7:1 cr) I am wanting to make 500+whp

I have since upgraded the turbo that is pictured in this photo to a Billet Turbonetics 6157.

On the verge of deciding if I should change manifolds/downpipe combo and wanted opinions.

Note - I am trying to do this on pump gas. E85 is limited around my area, but I am considering if i absolutely have to do this to make 500whp

Thanks guys

:wave:

Re: Log manifold how much power? | Open/closed wastegate discussion
 

With that mani you should be good to about 600whp after that they start to really become a restriction and cant flow very well. Even at 600whp gains can be made by changing to a mini ram or ram horn mani but log manis have been used with good results. Keep your setup the way it is now with the turbo and you will be fine. 500whp on that setup is very realistic.

Re: Log manifold how much power? | Open/closed wastegate discussion
 

I picked up about 80whp from switching from a log to a ramhorn and 93 to E85.

I would not push a log manifold past 450whp on 93 either. Been there done that.

Re: Log manifold how much power? | Open/closed wastegate discussion
 

Tubular logs are crap plain and simple. They work but all the runners intersect one another with now directional flow to the turbo. They cause a lot of back pressure and depending on the setup and cams and turbo being used it will be an issue. Your actually better off with a well designed cast log IE inline pro vs a tubular log.

I would NOT push past 400 on a tubular log with pump gas, back pressure, higher egt's make for a bad combo with pump gas

Re: Log manifold how much power? | Open/closed wastegate discussion
 

Divorced wastegates have made 30hp over one that was plumbed into the exhaust. Dyno proven

The old school way was to coat the dumptube in oil and do a pass/dyno pull and wherever the oil stopped burning off was how long the dumptube should be

Re: Log manifold how much power? | Open/closed wastegate discussion
 

I find it depends upon the turbocharger and camshaft used. I wouldn't use that as a general statement. As even Californidad (as an off-hand example) did quite well with his, and has no backpressure or EGT issues at all.

If it can't get the exhaust energy out fast enough from its collector, only then do I see an issue. Such as using 60lbs/min + sized turbos could pose an issue.

Re: Log manifold how much power? | Open/closed wastegate discussion
 

I can agree with that as being to broad of a statement. I should have been more clear in what I said. I did make mention that depended on cam and turbo combo. In any event I still feel a cast log will flow better

Re: Log manifold how much power? | Open/closed wastegate discussion
 

Interesting. i've found the exact opposite. In addition, the tubular log allows for better fitment and changeability of exhaust housings to a 4 bolt turbine or V-band.

With the cast manifolds, you're only limited to 5 bolt turbine housings, which limit options for the end user. Only the Inline Pro SS T4 model allows for other turbine housings (shown as an example below)

https://smg.photobucket.com/user/the...a/DSC03392.jpg
https://smg.photobucket.com/user/the...a/DSC03390.jpg

I gave up on these cast manifolds since 2004. I was tired of making sure they had the proper wastegate elbows for engine bays that have lower hood clearances (like your integra) and the limitations for repair if the cast had too many impurities in the molds. With different companies , you got varying results. With the tubular log, you have more options for turbocharger fitment, most are made with good schedule 10 steel, which is more consistent and easier to repair if there is a problem, and you can't send it back.

I'm so glad other Honda-enthusiast based companies do the tubular log. Everytime I see one of these Cast logs I think of 2 things.. 1999 (w/ Drag, Rev-Hard, and Fmax) , and Neukin, which would fit badly no matter how you sliced it.

Re: Log manifold how much power? | Open/closed wastegate discussion
 

Will be type R cams in my setup as well... so with mixed opinions I'm still not convinced.. should i attempt this or not.... Time to change manifolds?

I feel i have a better chance of selling this stuff if it's brand new, not used.. I don't want to put it together and not do what i'm expecting... I understand there is only one way to find out, but i know there are thousands of people on here.. thought i would ask

Re: Log manifold how much power? | Open/closed wastegate discussion
 

When you mean that you want to make "500whp +", I guess what we're saying is that you're at the threshold for using any kind of "log" manifold or using something else entirely. That's why you're getting mixed views (some from experience, others not so much) about this. The more the "+" in your "500+" comes into play, the less likely you'll be able to take any advantage of either tubular log or cast log for both now and later.

This is where use of the car, (purpose) and other supporting hardware really come into play. 300-350whp, sure, use the tubular log and be happy. Once you're past the 550whp mark, get something else entirely like a "mini-ram" , Bottom mount, or a Kooks "Ramhorn". But this also means that the purpose changes a bit.

So ask yourself which one is more the priority.. the 350whp or the 500whp..if the 500+ is more than a possibility as part of your plans, plan ahead and get the better manifold outside of these 2 choices. If its not as likely, stick with the tubular log.. Either way, I don't recommend recirculating into the downpipe unless you have to for visual inspection or other reasons.

It changes the behavior of larger compressor wheel / smaller turbine wheel combinations detrimentally. The changes and differences in power isn't the point on Hondas. (It makes a bigger difference on Subaru applications, because on average, they run more boost pressure which affects the wastegate's ability to vent excess pressure). You want less backpressure and turbulence.. so venting to atmosphere helps the turbocharger respond more easily with the same amount of boost pressure, and less turbulence in the exhaust stream (think fluid dynamics)..

I've had both recirculated dumps and open dumps. I went back to open dumps, and just changed where it dumped. As a result I smelled less exhaust fumes and such. But when you want 500whp +, with the amount of exhaust vent pressure that's going out of the downpipe, you want as little turbulence and exhaust merging as possible. So that's when you open it up.

The ball is in your court at this point.

Re: Log manifold how much power? | Open/closed wastegate discussion
 

Yeah back pressure becomes the issue with log mani's past a certain point even with cast mani's since they are not divided enough to really flow well like a tube style mani is. I think for the OPs goals a GO Auto mini ram is the best choice if he plans to go past 500whp. Having an open dump pipe is the best way to go for sure since recircing it into the down pipe has a large adverse effect on the exhaust flow out of the turbo. HP gains and increased turbo response has been proven with an open dump tube. I only suggested to the OP to keep it as it is just to keep it simple and not hack up a nice turbo kit. I suggest selling the mani and down pipe and putting the money to the mini ram, new down pipe and dump tube if he is serious about going past 500.

Re: Log manifold how much power? | Open/closed wastegate discussion
 

Thank you all for the informative posts.. My whole goal was to make over 500whp and track the car a few times and make it a weekend warrior.

I'm looking into changing manifolds, downpipe and open dump tube now.

Re: Log manifold how much power? | Open/closed wastegate discussion
 

Might be the better idea if going for "+".. ;). Just don't fall into that Top Mount nonsense

Re: Log manifold how much power? | Open/closed wastegate discussion
 

Log manifolds limit your camshaft selection.

You will create a lot of back pressure.. a lot.. I recommend on a log manifold running a longer duration exh cam, with a mild intake... This will give the exhaust some time to completely leave the cyl and give it somewhat of a "Bump", to start something along the lines of a scavaging effect as well to help suck down the BP.

I've tuned a lot of turbo cars.. in my day, and I've found the limit of a log manifold to be usually around 450ish whp.. on a properly tuned, motor setup and turbo setup.

Re: Log manifold how much power? | Open/closed wastegate discussion
 

Simple physics and fluid flow says logs are just an altogether shitty way to go. Having a good flowing manifold that directs the gases directly toward the turbine is a no brainer in my opinion. A tiny budget, low powered street car..I can endorse their use. I wish I had saved the dyno charts of some setups that I had gain 50-100 hp with no other changes. Get the wrong combo of cams and turbo and the car is totally choked with reversion, won't make power, won't take fuel etc. it's been well documented for ages now.

Re: Log manifold how much power? | Open/closed wastegate discussion
 

I have a spoolin performance log and type R cams. Tony at T1 said the Type R cams suck with a log manifold and said I would pick up 40hp back to back with a Ramhorn at the same psi.

My advice would be to change manifolds.

Re: Log manifold how much power? | Open/closed wastegate discussion
 

I dunno about that. Again, especially with Californiadad's setup doing exactly the opposite. And he used Edlebrock 4730s, which is a lot different than Type R cams. He also reached his goal of over 540whp in under 26psi of boost pressure. So, I find difficulty in subscribing to that yet.

I DO agree, that if he goes to the 600whp range, he'd be better off with something else.

Re: Log manifold how much power? | Open/closed wastegate discussion
 

I have a log from go autoworks (I have the street kit) and I'm at 400 whp at 13psi on 91 with Itr cams. Like others said you can take a log pretty far.

Re: Log manifold how much power? | Open/closed wastegate discussion
 

They work, thats for sure. But I've seen 30+ hp gains from a switch to a mini ram/something with a real collector as the same boost level

Re: Log manifold how much power? | Open/closed wastegate discussion
 

for larger turbos over 60lbs/min, sure. For the smaller ones, not so much of a difference. But its not even about power. The manifold type changes behaviour of the turbocharger used as well. so you have to look at both the turbocharger and the exhaust manifold in question. Its not a one-size-fits-all scenario. Like anything else, there are other factors involved.

Re: Log manifold how much power? | Open/closed wastegate discussion
 

Ya, I kinda stopped paying attention at Turbonetics.