hey everyone,

-im having a hard time sourcing a stainless t4 divided HKS manifold for a GT35r, as they are 'discontinued' on the hks website. does anyone know where or how to best locate one?

-in the mean time the fd cast hks manifold looks pretty decent, just not as good as the stainless to me.

-there's a feed twin turbo manifold floating around the forums and i wanted to get your opinions about that. it seems like it could be very expensive and complicated and im not sure if there's much upside when new turbos are great and im not looking for more than 370-400whp. im more about a good responsive feel.

*i saw the feed manifold in a jdm parts magazine catalog when i was still in highschool and remember drooling at its organic and artistic shape. so i dont know if im just dreaming or if its something other, more experienced, turbo guys would agree is worth the pursuit. i have an emotional response to it and thats not always a good thing.

*i also have high compression rotors on a 13b-re cosmo, which can only handle 10-12 psi. im not sure how this factors into the gt35 vs feed twin turbo thing.

*my last option would be to keep it NA and not have to worry about upgrading brakes, v mount, piping/exhaust, changing out secondaries (already have stand alone and full fuel), or changing out the differential (have tii trans and miata 4.3 torsen). its at a pretty finished and good state now. im not sure if i should upset this balance. could always find a road race header at rotaryshack. currently at 236whp and 189tq.

hks cast/SS vs feed twin vs keeping it N/A simple. and where to find SS HKS?

thanks for all knowledge and feedback!

 

the twin turbo manifolds are very very cool, and the demo cars with that setup make big power. however you have to buy 2 turbos instead of one, and then plumb them in, so its more expensive and complex than just a single.

the HKS cast manifold is nice, its cast, so reliability is good. its divided, which is good, and it actually fits a T04S with the airpump, so it is emissions legal, which is big for the one person who has to deal with that (me!). its my first choice for a manifold.

the tubular HKS manifold is good too, i haven't looked into it much, as i need to keep the airpump, but i believe the T04Z kit comes with the tubular manifold, still

 

I honestly don't know one manifold from another, but I thought the waste gate pipes should angle away from the engine to allow for more flow through the waste gate.

The tubular manifold in the first photo has the pipes exiting at a right angle to flow. Won't this potentially allow boost creep?

 

I have both manifolds.

The cast and tubular are completely different in terms of sizing and placement of the turbo. If you are running a GT35r at low boost, I would pick up the cast as it is available and more reliable.

Make your life easy get the Banzai adapter while you are at it for a Tial 44.

 

I have a spare HKS Divided T4 Stainless Tubular manifold. I was going to use it when my engine let go but the engine died at a time when I didn't have the money/drive for a single turbo so I put on highflow twins.

Message me if you are serious.

 

Precision 6266 also fits with the air pump on the Cast mani, just swapped my broke t04s for one

 

Those HKS cast manifolds are boost creep city in my experience. I have tuned a lot of them, even with a tial 44mm that crept. We have FD manifolds in stock ready to ship. A recent forum member swapped from a HKS cast to our FD manifold( nothing else was changed) and noticed a considerably gain in top end power. He has owned and tracked the car for years in CA, so he is very familiar with how it performs.

Turblown Engineering FD3S RX-7 Twin Scroll Turbo Manifold

 

I know you have a business to run but this is is far from my experience.

26psi running stable with that exact manifold and a Tial MVR, on one of your older turbos fwiw.

 

This make no sense at all. Even the worst manifold will hold HIGH BOOST. The higher the boost the easier it is to maintain and hold boost. No manifold is going to creep with a 26 psi target. Creep happens when trying to hold lower boost levels. I am guessing the 10 to 14 psi area is where this manifold may creep but that is just a guess.

 

I have the HKS tubular and its been great. Holds low boost of 10-11 psi no problem on a 35r, my version came with a 4-bolt wastegate flange that I had cut off and a tial v44 v-band welded on. I think this manifold has been unavailable for separate purchase for many years now and was only available with the very expensive full HKS turbo kits.

 

There's multiple versions of a HKS tubular, best bet is to watch the Japanese auctions when they come up from time to time.....and the feed one was on there about a year ago.

No experience with a 35, but have found creep is an issue with them too, if something more modern/larger is installed.

 

So you got the smoking problem to go away? Was a smaller restrictor needed? I do remember you



There are TON of variables to the overboost scenario.

If you run a 3" downpipe and move to a 3.5" or 4" and the turbo can breath properly it will make a system with poor wastegate placement instantly start to creep.

Runner lower boost pressures is usually where it shows up the most, but even high flowing setups at higher boost pressures it can be an issue too. I recently tuned a semi-pport methanol car that did this( similar manifold to my twin wg design).

 

What do you guys think of doc race manifolds? I could get a smoking deal on a brand new one.

 

I am about to mate a efr 8374 to my hks ss manifold w/ a mvr 44mm wastegate. Will be running a 3.5inch dp and mp. Will let you know if it creeps @15psi.


For the record. I had a hks cast /44mm mvr and a td61. Held 15psi well

 

Car stopped smoking however, did not change the oiling system it just stopped same restrictor and drain for what I think must be 4 years now.

The smoke stopped around 1000km at the same time as the turbo developed some play back and forth. The play has not increased and the smoke has not reappeared in 15000km of driving.

People who drive my car do like the performance and the ontime of the turbo.

At 26 psi now not seeing the rwhp increases I would expect vs 23 & 20 psi so will be testing to increase flow changing exhaust components. From 23-26 psi I gained 10 rwhp on the topend but 25-30 from 5-7k rpm.

So maybe I should have specified.

I have run this turbo from 10psi to 26psi and have not experienced issues controlling boost.

I did have oscillation from a previous wastegate (Synapse)but no creep.

 

Makes a lot more sense.

 

I have run multiple different turbos on the FD HKS cast manifold in several different configurations (GT35R, T04Z, T04E, etc) in FB, FC, and FD, the only time I have seen any creep issue was when trying to use the old HKS 38mm Standard wastegate with a GT35R on an FD. This was the reason we came up with the Tial MVR adapter in the first place.

We have customers running anywhere from 11psi-26psi depending the power they are looking for, not one of them has a problem with creep.

 

I will echo the comments of Banzai and dradon. I have the HKS Cast manifold, bought from Banzai. I went with an Ebay HKS knockoff gate and a 3" exhaust with Cat. I have run 7 psi on the spring to 8000, rock solid. My experience for what its worth.

 

I've had similar results. Introduce too much flow into the system and they begin to have trouble controlling boost. There are many factory to consider such as porting, exhaust diameter, turbo size, boost controller choice, tuning, etc. so that is why on some cars you get away with it, others not. Personally I've seen a 20+ hp gain on top from switching from a HKS cast manifold to my equal length tubular manifold. The other thing is cast iron is a huge heat sink, and placement so close to the motor and intake manifold is far from ideal. That being said the HKS cast manifold is relatively inexpensive and I have yet to see one crack, so I can see why people consider it.

Banzai-Racing I've had the same thing happen with the old 38mm wastegate. Switch it out and the issue is usually resolved. I actually installed a overpriced FEED (HKS re-branded) T04S kit for a customer who was set on it against my recommendations and it came with the under-sized 38mm wastegate and HKS cast manifold. We couldn't run less than 12 lbs of boost in that car in the cold and it would creep to 14 or 15. Ended up just tuning for 15lbs so now he has to run it at that instead of the initial 10lb low boost setting he wanted. Eventually I'll get your adapter and put a 44mm Tial on it when he is ready.

<track>7 be careful with that Ebay wastegate. I've seen quite a few fail. Sometimes they stick open and you just lose boost but I have seen a few fail completely and cost an engine.

 

I have a crate here of around 20 turbosmart wastegates new and old that leak, have completely failed, cause engine failures etc.

 

Which model wastegates are these? I know some of their older products had issues but the word is the newer units are pretty good quality.

 

I have 2 of their latest and greatest 60m gates with diaphragms that leak. Gates are less then 1000km old. Not covered under warranty(I won't bother righting the excuse here they gave) so we binned them.