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Hello all,
I'm a long time lurker and reader but never posted
I own a '99 FD3S and I am wondering at what point the twin turbo exhaust manifold becomes a limitation and a risk.
Currently my car is 100% stock.
I've always read about how it's material composition means it retains a lot of heat that then transfers it to the engine, damaging it.
I realise that a single turbo setup is better than a twin setup for heat management and simplicity by removing the vacuum setup, I am just not sure at what point the pros outweigh the cons of a single turbo conversion(mainly cost, deviating from OEM that may hurt value of car?, any issues that usually arise with custom setups etc.)
I am looking into a Haltech 2500 and cooling mods to modernise the car with diagnostics and tuning, however I'm on the fence if I should move on to a single turbo setup or not.
The car is only used for spirited street driving and cruising and it is not a daily.
Max hp goal would be at absolute max ~350whp but more realistically I think I'd be more than ok with 300-320whp.
Considering the above, can a twin turbo setup with ECU + upgraded cooling work for the use I am mentioning or am I still risking the engine health ?
TIA!
Last edited by Vasilis Olympios; 03-27-22 at 04:52 AM.
Reason: edit
Long story short, for your power level goals, you should retain a fully functional set of sequential twins. There’s a lot of reliability mods in the FAQ section. You can look at the build section too and also Banzai Racing’s website where he documents his different builds for the twins. There’s a gold thread he puts up about small mods and how you can push almost 100 hp of reliable power with a power FC. Someone should link that.
Just like building a PC should go with upgrades in logical increments. I went full send on my FD with overkill cooling with a v-mount and a lot of other mods but I was antsy. As others advised me, would recommend doing your build and upgrades in phases in terms of most performance/reliability : cost first.
Xavier, RotaryExtreme and others can guide you on the tuning aspect. I am new myself but the power Fc has something called FC tweak that may be an option to ponder. A lot of knowledgeable folk swear by it, and attest to how it’s modernized the power FC. Definitely worth looking into, and if you ever decide to go single, can sell the PFC if you want to go haltec (and won’t need the 2500).
Before you decide what ecu you are going to get consult with the person who is going to tune it first. Based on your name and the 99spec car i am assuming you are from Cyprus (unless you have a 99spec rx7 in Greece somehow) . As far as i know no one with rotary experience will tune an elite ecu in Cyprus and and pretty much no one in Greece will do it. You will probably be better off with a link ecu as everyone is using link ecu over there.
As for the limitation of the manifold it all depends on the condition of your existing manifold. They are 20+ years old so cracks will be inevitable. From what you are explaining it appears that a properly running twin turbo is probably your best option. If you want to simplify the system you can convert it into non sequential but nothing beats an oem sequential system that is running properly for 310-320 whp
if you decide to go for the haltech get the 2500 if you are planning to stick to the twin turbo system
A power fc is also a good option that works for 85% of the people out there. Its not modern but it does the job. Obviously the haltech/link etc are superior. No one will deny that but the power fc has been a solid option for years
Cracking of the turbine housing (FYI the manifolds hardly ever crack, the turbine housing (turbo hot side) is what always cracks) is more common on the original N3A1 turbos that the 93's had. The later cars either had the N3C1 or the N3G1 "99 Spec" turbos, they have higher nickel content in the manifolds. They can crack but it's much less of a problem. Cracking is really not that big of a deal, the only time it's a problem is if the crack goes under the gasket mating surface and blows out the gasket or the wastegate cracks so it doesn't seal well and you lose boost.
350hp to the ground with stock emissions and drivability. This is a killer way to go.
Also it's well worth posting your general location in your user profile, many questions need that information for a proper answer. Even if it's the country or region you are in.
All that said, I haven't ever seen evidence that the cast iron mass of the stock twins results in engine failure or something like that. Bad tuning and poor maintenance is far more likely. Also the FD engines are really good for 80-100,000 miles at which point they need a rebuild before they totally let go.
I don’t see the stock manifold as being a big contributor to shortening engine life. Engine heat management…or lack of it, yes. All the normal things…keeping coolant fresh, monitoring temps, good hoses etc. In your climate you could probably run a higher percentage of distilled water than most which helps. A good quality aftermarket radiator, lowering the fan threshold with the ECU or an FC thermoswitch, and a simple water injection system will also do ALOT for engine heat management.
I see the manifold more as a source of under hood heat soaking. And that mitigation is different.
Before you decide what ecu you are going to get consult with the person who is going to tune it first. Based on your name and the 99spec car i am assuming you are from Cyprus (unless you have a 99spec rx7 in Greece somehow) . As far as i know no one with rotary experience will tune an elite ecu in Cyprus and and pretty much no one in Greece will do it. You will probably be better off with a link ecu as everyone is using link ecu over there.
As for the limitation of the manifold it all depends on the condition of your existing manifold. They are 20+ years old so cracks will be inevitable. From what you are explaining it appears that a properly running twin turbo is probably your best option. If you want to simplify the system you can convert it into non sequential but nothing beats an oem sequential system that is running properly for 310-320 whp
if you decide to go for the haltech get the 2500 if you are planning to stick to the twin turbo system
A power fc is also a good option that works for 85% of the people out there. Its not modern but it does the job. Obviously the haltech/link etc are superior. No one will deny that but the power fc has been a solid option for years
Yes I am in Cyprus that's correct. I've heard about some in Greece that deal with Haltech & rotaries but I was mostly leaning towards remote tuning from EU/US, I contacted some of the usual names that pop up when you search for this.
Unfortunately, as far as I know, Link does not support the twins so I ruled them out (I don't know if something changed since).
Regarding non-seq, I am not interested in that anyway so I am guessing a refresh of the components of the sequential system and keeping the stock way of connecting everything (maybe a simplified version of sequential?)
Originally Posted by Jatt
Long story short, for your power level goals, you should retain a fully functional set of sequential twins. There’s a lot of reliability mods in the FAQ section. You can look at the build section too and also Banzai Racing’s website where he documents his different builds for the twins. There’s a gold thread he puts up about small mods and how you can push almost 100 hp of reliable power with a power FC. Someone should link that.
Just like building a PC should go with upgrades in logical increments. I went full send on my FD with overkill cooling with a v-mount and a lot of other mods but I was antsy. As others advised me, would recommend doing your build and upgrades in phases in terms of most performance/reliability : cost first.
Xavier, RotaryExtreme and others can guide you on the tuning aspect. I am new myself but the power Fc has something called FC tweak that may be an option to ponder. A lot of knowledgeable folk swear by it, and attest to how it’s modernized the power FC. Definitely worth looking into, and if you ever decide to go single, can sell the PFC if you want to go haltec (and won’t need the 2500).
I was under the impression the PFC even if proven is now considered primitive, that's why I went looking into Adaptronic first and Haltech after.
Originally Posted by j9fd3s
if you dig deep Speed of Light did some flow testing on a flow bench, and the manifold isn't a limitation in flow.
I am sorry I meant a limitation in reliability/performance regarding heat generation and management, not flow, my bad!
Originally Posted by Sgtblue
I don’t see the stock manifold as being a big contributor to shortening engine life. Engine heat management…or lack of it, yes. All the normal things…keeping coolant fresh, monitoring temps, good hoses etc. In your climate you could probably run a higher percentage of distilled water than most which helps. A good quality aftermarket radiator, lowering the fan threshold with the ECU or an FC thermoswitch, and a simple water injection system will also do ALOT for engine heat management.
I see the manifold more as a source of under hood heat soaking. And that mitigation is different.
The plan for cooling would be an upgraded radiater and intercooler (Greddy vmount kit seems like a good solution even if it's a bit costly), upgrading plastic tanks to metal ones, I saw some posts about RX-8 fans performing better, FC thermostat and I also used a water injection system in a previous car so I am also going for that in the FD as well. I was looking into ceramic coating parts of the turbo system/manifolds etc. but so far I haven't found concrete results that it is actually worth doing.
Originally Posted by DaleClark
You'll be fine, you are over-thinking this.
Also it's well worth posting your general location in your user profile, many questions need that information for a proper answer. Even if it's the country or region you are in.
All that said, I haven't ever seen evidence that the cast iron mass of the stock twins results in engine failure or something like that. Bad tuning and poor maintenance is far more likely. Also the FD engines are really good for 80-100,000 miles at which point they need a rebuild before they totally let go.
Dale
I apologise, I didn't realise I logged in through Facebook and the profile is really empty! Fixed the location part now, thanks!
Last edited by Vasilis Olympios; 03-27-22 at 10:33 AM.
V mount with proper ducting. Can look at a vented hood to help and I have the Aquamist that I have spraying above 7psi to help keep the internal temps lower.
I am currently in the process of switching from a Power FC to a Haltech Elite 2500. I will update my build thread in 3-6 months when it is done. I think Dale Clark or DJ Seven (dont remember who said it first) put it best when he said go for the single if your car already has a single or has been converted to non sequential. Go for sequential if you still have the parts and are not concerned with making huge power.
I am currently in the process of switching from a Power FC to a Haltech Elite 2500. I will update my build thread in 3-6 months when it is done. I think Dale Clark or DJ Seven (dont remember who said it first) put it best when he said go for the single if your car already has a single or has been converted to non sequential. Go for sequential if you still have the parts and are not concerned with making huge power.
That's a good thread that I didn't notice! Now I'm wondering how reliable a 100% stock RX7 can be
The plan for cooling would be an upgraded radiater and intercooler (Greddy vmount kit seems like a good solution even if it's a bit costly), upgrading plastic tanks to metal ones, I saw some posts about RX-8 fans performing better, FC thermostat and I also used a water injection system in a previous car so I am also going for that in the FD as well. I was looking into ceramic coating parts of the turbo system/manifolds etc. but so far I haven't found concrete results that it is actually worth doing.
I may have misunderstood….when you talked about the limitations of stock sequential manifold and your suspicion that it was responsible for engine damage I thought of engine cooling, not underhood heat or IATs. Some of what you mention above help mitigate underhood heat, such heat-coating the DP. Some of the above affect engine cooling, like a larger all-aluminum radiator, water injection and the FC thermoswitch (not thermostat), and possibly the RX8 fans. Some affect intake temperatures like a V mount…and depending on the system, water injection may also help IATs. But these are all different cooling concerns.
I think the sequential manifold is generally pretty robust and it’s affect on engine longevity minimal or non-existent.
I may have misunderstood….when you talked about the limitations of stock sequential manifold and your suspicion that it was responsible for engine damage I thought of engine cooling, not underhood heat or IATs. Some of what you mention above help mitigate underhood heat, such heat-coating the DP. Some of the above affect engine cooling, like a larger all-aluminum radiator, water injection and the FC thermoswitch (not thermostat), and possibly the RX8 fans. Some affect intake temperatures like a V mount…and depending on the system, water injection may also help IATs. But these are all different cooling concerns.
I think the sequential manifold is generally pretty robust and it’s affect on engine longevity minimal or non-existent.
Yes I was indeed talking about the potential engine damage since I've been reading that since the manifold is cast iron, it retains heat that transfers to the engine therefore damaging it. The way I understood is if you have a hot piece of iron in close proximity to the engine thus radiating heat to it and cooking parts of it? Part of why the single turbo is a good idea for cooling (less stuff, stainless steel manifold etc.).
Since English isn't my first languge, the risk that I misunderstood something is there
Yes I was indeed talking about the potential engine damage since I've been reading that since the manifold is cast iron, it retains heat that transfers to the engine therefore damaging it. The way I understood is if you have a hot piece of iron in close proximity to the engine thus radiating heat to it and cooking parts of it? Part of why the single turbo is a good idea for cooling (less stuff, stainless steel manifold etc.).
Since English isn't my first languge, the risk that I misunderstood something is there
I think you are being overly precautious. The tips sgtblue offered are really all you need for a reliable rx7 that will last you a long time. When I did my rebuild I had my exhaust manifold ceramic coated to help with heat management, and so far I have not noticed a huge difference. Here is a picture.
I would say most of FD failure, if not most rotary failure is from poor maintenance. The car may have sat for a while and the previous owner never changed the coolant or forgot to check the oil regularly. As far as getting rid of engine bay heat, if your car is left hand drive, replacing the stock downpipe with either a RHD downpipe (which has its own heat shielding around it) or using a ceramic coated catless downpipe such at the ceramic coated HKS pipe (I have pictured below) will significantly reduce unhood heat.
Finally, the thing you may be confused about is the wastegate on the exhaust housing side of the turbocharger not the exhaust manifold itself. The FD has an internal wastegate that is prone to cracking. It is made of cast iron. If it cracks bad enough you will not get full boost and the exhaust housing must be replaced. Below is a picture of mine. It is cracked but I am still getting enough boost.
Just to reiterate, the 1st picture is the exhaust manifold. This requires no special attention and is not known to have problems.
The 2nd picture is a downpipe. These are known for generating a lot of heat, but are easily fixed.
The 3rd picture is the turbocharger exhaust housing. They too are made of cast iron and are known for cracking, but no special attention is needed, unless you cannot get full boost.
I apologies if you already knew this. I sounds like there may have been some confusion as to what parts are what.
Your English, at least the printed version, is great. Far better than my skills in the two foreign languages I’ve studied.
Do you have a link or reference to where you were reading this about the stock turbo manifold?
Thank you!
It was mostly pieces here and there on the forum after looking into the single vs twins debate. People saying the manifold retains heat that transfers to engine as I said, twins generating way more heat than a single cooking up any component in proximity or that the manifold is a bad design/has a bad location for "breathing".
I'm wondering how much of this is true and how much is just people upping the boost on the twins beyond their efficiency range (meaning they do overheat) and blaming the concept and configuration rather their own approach to it. I wonder if for example the BNR twins have these issues when running higher boost.
I was looking into blankets/wraps etc. but they have the potential of being a fire hazard or masking issues so thus far, my only "extra" step is looking into some custom heat shielding combined with thermal coating the twin turbo system and so on.
If I'm not mistaken, my '99 does not have a precat that was found in USDM cars which is also a big source of heat if I'm correct?
I think you are being overly precautious. The tips sgtblue offered are really all you need for a reliable rx7 that will last you a long time. When I did my rebuild I had my exhaust manifold ceramic coated to help with heat management, and so far I have not noticed a huge difference. Here is a picture.
I would say most of FD failure, if not most rotary failure is from poor maintenance. The car may have sat for a while and the previous owner never changed the coolant or forgot to check the oil regularly. As far as getting rid of engine bay heat, if your car is left hand drive, replacing the stock downpipe with either a RHD downpipe (which has its own heat shielding around it) or using a ceramic coated catless downpipe such at the ceramic coated HKS pipe (I have pictured below) will significantly reduce unhood heat.
Finally, the thing you may be confused about is the wastegate on the exhaust housing side of the turbocharger not the exhaust manifold itself. The FD has an internal wastegate that is prone to cracking. It is made of cast iron. If it cracks bad enough you will not get full boost and the exhaust housing must be replaced. Below is a picture of mine. It is cracked but I am still getting enough boost.
Just to reiterate, the 1st picture is the exhaust manifold. This requires no special attention and is not known to have problems.
The 2nd picture is a downpipe. These are known for generating a lot of heat, but are easily fixed.
The 3rd picture is the turbocharger exhaust housing. They too are made of cast iron and are known for cracking, but no special attention is needed, unless you cannot get full boost.
I apologies if you already knew this. I sounds like there may have been some confusion as to what parts are what.
Yes this is perfect. Now it's more clear in my head. I already have an RHD car so I suppose the downpipe needs no further attention at this point.
You mentioned you haven't noticed a huge difference from ceramic coating but is there at least measurable difference?
In my opinion, the turbo manifold will do nothing that will cause problems. I've never seen any evidence of that. Also while it gets really hot it's way below the heat that is running in the combustion chamber.
JDM cars don't have a pre-cat, fortunately. But the stock downpipe isn't great, a good aftermarket downpipe will bump power up. Ceramic coating as Stephen talked about is a great idea on the downpipe, that's the best "bang for the buck" on what needs coating.
The twins don't blow engines. Too much boost with too much timing, lean air fuel ratios, that is what blows engines. You can do it just as fast with a single turbo.
In my opinion, the turbo manifold will do nothing that will cause problems. I've never seen any evidence of that. Also while it gets really hot it's way below the heat that is running in the combustion chamber.
JDM cars don't have a pre-cat, fortunately. But the stock downpipe isn't great, a good aftermarket downpipe will bump power up. Ceramic coating as Stephen talked about is a great idea on the downpipe, that's the best "bang for the buck" on what needs coating.
The twins don't blow engines. Too much boost with too much timing, lean air fuel ratios, that is what blows engines. You can do it just as fast with a single turbo.
Dale
So for starters, If I just replace any hoses for the seq. system and perhaps the solenoids and stick with OEM ECU since I don't have a pre-cat, can we assume the car would be reasonably reliable? If it matters, the car has even the stock catback on it, nothing modded
Basically…IMO, all reliability starts with engine cooling. Having a sound engine cooling system, and the ability to monitor it, is first. Good hoses, all metal radiator, metal AST, fresh coolant, fan thermoswitch or lowered threshold thru an ECU, perhaps water injection, a decent aftermarket temperature gauge (or the ability to monitor temps thru an ECU). These are the things I’d start with for reliability.
If or when modifications are made to the intake or exhaust systems, then keeping the engine at stock boost levels comes next…IMO.
And finally, back to the thread title …the stock manifold is heavy, and a source of underhood heat that’s hard to avoid. But if you stay with the stock turbos it’s not really a limitation or a threat to the engine.
So for starters, If I just replace any hoses for the seq. system and perhaps the solenoids and stick with OEM ECU since I don't have a pre-cat, can we assume the car would be reasonably reliable? If it matters, the car has even the stock catback on it, nothing modded
I would get a boost gauge and see what your boost pattern is to start with then go from there. Don't just change all the hoses, many times that ends up creating a lot more problems. The stock hoses are fine until you touch them and try to remove or replace, that's when they break.
The car can be perfectly reliable with bad boost. More important is cooling, all fluids up to date, good tires, good brakes, etc.
I would get a boost gauge and see what your boost pattern is to start with then go from there. Don't just change all the hoses, many times that ends up creating a lot more problems. The stock hoses are fine until you touch them and try to remove or replace, that's when they break.
The car can be perfectly reliable with bad boost. More important is cooling, all fluids up to date, good tires, good brakes, etc.
Dale
most of the hoses only see vacuum as well, so its best to just leave them alone.
03-27-22, 04:48 AM
