RB26 #5 amd #6 compression low........rebuild time

[GohiraDave]

Hi everyone!

As the title states, I have low compression in 5 and 6. I have not done a leakdown test yet but I plan to soon. I am starting my shopping list for a fresh rebuild. I've owned her for 9 years and never had to do any major maintenance other than a clutch swap and swapping out rear subframe bushings, so she has been good to me 😁. I'm not looking for huge power but reliability is #1.  I use my car on weekends for some highway pulls and occasional autocross. I was originally looking to stay 2.6 with forged pistons, rods and a 33 crank but for a couple grand more I can go with the HKS 2.8 stroker to help a bit on the low end. I have stock turbos with steel wheels but I plan on upgrading those too. Here is the list I've put together so far.

 

HKS 2.8 stroker step zero (86.5mm)

ACL bearings, APR studs for head and main

Enlarged oil drain return from the head to the sump

New OEM water pump and HKS oil pump

GTX2867R Gen 2 turbos 0.64 A/R (if anyone has these installed, please send some feedback as there isn't too much info that I can find on them)

New heater and coolant hoses, complete gasket set and timing belt

 

These are the main parts installed

Power FC (Yeah, its ancient) but I plan on swapping it out for a Haltec platinum pro

Greddy turbo timer and boost controller

ORC twin disk clutch

3.5 in BeeR exhaust, down and mid pipes. Unknow aftermarket dumps.

Koyo radiator and Blitz intercooler

Apexi pod filters

 

Parts on hand

Deatscherks 800cc low inpedance injectors

Nismo fuel pump

Tomei adjustable cam gears

 

Tell me what do you think! Also for my 2.8 guys, was a bore necessary or was honing enough to install the 86.5mm pistons without issue? 

Thanks for the help and I've added a couple of pictures of my ride! 🤘

 

[Murray_Calavera]

3 hours ago, GohiraDave said:

Enlarged oil drain return from the head to the sump

New OEM water pump and HKS oil pump

GTX2867R Gen 2 turbos 0.64 A/R (if anyone has these installed, please send some feedback as there isn't too much info that I can find on them)

Power FC (Yeah, its ancient) but I plan on swapping it out for a Haltec platinum pro

 

Parts on hand

Deatscherks 800cc low inpedance injectors

Nismo fuel pump

Tomei adjustable cam gears

 

Tell me what do you think! Also for my 2.8 guys, was a bore necessary or was honing enough to install the 86.5mm pistons without issue? 

I'll throw my 2c in - 

Getting a breather on your sump will help a lot more for oil control issues (rather then just enlarging oil drains). Have a read of the oil control thread if you haven't yet. 

You'll need a larger and baffled sump if you're running an upgraded oil pump. You'll probably get recommendations to look at a Nitto oil pump instead of the HKS pump. 

Would you consider going single turbo? 

The Haltech pro plug in is over 13 years old now, I would also consider it ancient. I'm still using one and can't wait to upgrade. 

You can do a lot better then a Nismo fuel pump these days. I'd be looking at a Walbro 525 or similar.

I'm guessing your block hasn't been bored out yet? You won't get a 86.5 mm piston into a 86 mm bore, so yep it will need to be bored out to accept the 86.5 mm piston. Your machinist will use the pistons you'll be running to set the piston to cylinder wall clearance when you drop the block off for machining. 

Side note, the GTR looks really tidy

[r32-25t]

The turbos don’t work, there has been quite a few people who have tried putting gtx turbos into the original housings and they end up very laggy and don’t make any where near the power they are expect to.

You need a 9L extended sump with baffles or it will surge and with the big pump probably empty it out at high revs 

The rear head drain is a must 

the fuel pump and injectors are to small 

go the elite 2500 with plug in adapter and fit oil and fuel pressure sensors in it to use for engine protection 

what fuel do you intend on running?

[joshuaho96]

5 hours ago, GohiraDave said:

Hi everyone!

As the title states, I have low compression in 5 and 6. I have not done a leakdown test yet but I plan to soon. I am starting my shopping list for a fresh rebuild. I've owned her for 9 years and never had to do any major maintenance other than a clutch swap and swapping out rear subframe bushings, so she has been good to me 😁. I'm not looking for huge power but reliability is #1.  I use my car on weekends for some highway pulls and occasional autocross. I was originally looking to stay 2.6 with forged pistons, rods and a 33 crank but for a couple grand more I can go with the HKS 2.8 stroker to help a bit on the low end. I have stock turbos with steel wheels but I plan on upgrading those too. Here is the list I've put together so far.

 

HKS 2.8 stroker step zero (86.5mm)

ACL bearings, APR studs for head and main

Enlarged oil drain return from the head to the sump

New OEM water pump and HKS oil pump

GTX2867R Gen 2 turbos 0.64 A/R (if anyone has these installed, please send some feedback as there isn't too much info that I can find on them)

New heater and coolant hoses, complete gasket set and timing belt

 

These are the main parts installed

Power FC (Yeah, its ancient) but I plan on swapping it out for a Haltec platinum pro

Greddy turbo timer and boost controller

ORC twin disk clutch

3.5 in BeeR exhaust, down and mid pipes. Unknow aftermarket dumps.

Koyo radiator and Blitz intercooler

Apexi pod filters

 

Parts on hand

Deatscherks 800cc low inpedance injectors

Nismo fuel pump

Tomei adjustable cam gears

 

Tell me what do you think! Also for my 2.8 guys, was a bore necessary or was honing enough to install the 86.5mm pistons without issue? 

Thanks for the help and I've added a couple of pictures of my ride! 🤘

 

I think your idea of "not huge power" vs my idea of "not huge power" is very different. 2867s are big turbos and arguably too big for the factory twin turbo setup. If you want to stay with factory twin turbo to reduce the amount of unknowns in your build I wouldn't go larger than 2860s. Especially if reliability is a concern at all.

[robbo_rb180]

17 hours ago, GohiraDave said:

 

Power FC (Yeah, its ancient) but I plan on swapping it out for a Haltec platinum pro

 

That model is so old. An elite series with knock control would be the go but need the silly patch harness.

Link ecu do a g4x plugin with more functionality for a better price and not locked to one environment of product.

[GohiraDave]

22 hours ago, Murray_Calavera said:

I'll throw my 2c in - 

Getting a breather on your sump will help a lot more for oil control issues (rather then just enlarging oil drains). Have a read of the oil control thread if you haven't yet. 

You'll need a larger and baffled sump if you're running an upgraded oil pump. You'll probably get recommendations to look at a Nitto oil pump instead of the HKS pump. 

Would you consider going single turbo? 

The Haltech pro plug in is over 13 years old now, I would also consider it ancient. I'm still using one and can't wait to upgrade. 

You can do a lot better then a Nismo fuel pump these days. I'd be looking at a Walbro 525 or similar.

I'm guessing your block hasn't been bored out yet? You won't get a 86.5 mm piston into a 86 mm bore, so yep it will need to be bored out to accept the 86.5 mm piston. Your machinist will use the pistons you'll be running to set the piston to cylinder wall clearance when you drop the block off for machining. 

Side note, the GTR looks really tidy

Great info, I'll check out the oil thread. I have thought about single but my budget is pretty tight especially with the possible addition of the 2.8. That is why i am looking into bolt on turbos. That is also why I already have the Nismo pump and injectors. I was planning on upgrading the turbos until my ringlands thought differnt. The engine is still installed, lost compression a week ago. I'm in the planning stage right now. Thanks again!

[GohiraDave]

21 hours ago, r32-25t said:

The turbos don’t work, there has been quite a few people who have tried putting gtx turbos into the original housings and they end up very laggy and don’t make any where near the power they are expect to.

You need a 9L extended sump with baffles or it will surge and with the big pump probably empty it out at high revs 

The rear head drain is a must 

the fuel pump and injectors are to small 

go the elite 2500 with plug in adapter and fit oil and fuel pressure sensors in it to use for engine protection 

what fuel do you intend on running?

Got it, thanks! I will stretch the wallet for the elite 2500. I was going through the old threads for turbos and was leaning torwards a set of -5s. I figured the were old tech by now so I'll keep researching turbos. Here in Las Vegas we have 91 with a few stations that sell E85 and 100 octane race gas. With the addition of the 2500 it would be nice to add flex fuel. More to come.

[GohiraDave]

21 hours ago, joshuaho96 said:

I think your idea of "not huge power" vs my idea of "not huge power" is very different. 2867s are big turbos and arguably too big for the factory twin turbo setup. If you want to stay with factory twin turbo to reduce the amount of unknowns in your build I wouldn't go larger than 2860s. Especially if reliability is a concern at all.

Understood. I'm still in research mode for new turbos and yes, reliability is #1. I appreciate it!

[GohiraDave]

8 hours ago, robbo_rb180 said:

That model is so old. An elite series with knock control would be the go but need the silly patch harness.

Link ecu do a g4x plugin with more functionality for a better price and not locked to one environment of product.

Thats crazy, a coworker just told me about link today. It must be a sign LOL. I'll chek them out. Thanks!

[joshuaho96]

9 hours ago, robbo_rb180 said:

That model is so old. An elite series with knock control would be the go but need the silly patch harness.

Link ecu do a g4x plugin with more functionality for a better price and not locked to one environment of product.

AFAIK you can get around some of the Haltech vendor lock-in but you have to be willing to put in work to reverse engineer things. I did this recently for the AMP Superseal 1.0 connectors. If there's interest I can post up all the little things I learn along the way.

37 minutes ago, GohiraDave said:

Got it, thanks! I will stretch the wallet for the elite 2500. I was going through the old threads for turbos and was leaning torwards a set of -5s. I figured the were old tech by now so I'll keep researching turbos. Here in Las Vegas we have 91 with a few stations that sell E85 and 100 octane race gas. With the addition of the 2500 it would be nice to add flex fuel. More to come.

If you want "modern -5s" AFAIK the GTX2860R gen 2 is available in bolt-on form for the RB26. Speed Academy ran them but I'm not sure the results are all that impressive. A lot of this is probably because the factory piping is just restrictive.

[robbo_rb180]

34 minutes ago, joshuaho96 said:

AFAIK you can get around some of the Haltech vendor lock-in but you have to be willing to put in work to reverse engineer things. I did this recently for the AMP Superseal 1.0 connectors. If there's interest I can post up all the little things I learn along the way.

If you want "modern -5s" AFAIK the GTX2860R gen 2 is available in bolt-on form for the RB26. Speed Academy ran them but I'm not sure the results are all that impressive. A lot of this is probably because the factory piping is just restrictive.

The time and skill it takes to reverse engineer is hard for 98% of people that just want to plugin and go. Especially when it comes to displays and modules.
We have a guy in Australia that has finally put out a how to for unlocking the link ecu password protection.

For the OP who ever is tuning the car will recommend an ECU that they may be more comfortable/familiar with too so have a chat with them on what they use normally.
With the turbos if not aiming for big power and want the stock look have a look at high flowing current turbo's, @hyper-gear have a great reputation over here.

[PLYNX]

GohiraDave said - "Here in Las Vegas we have 91 with a few stations that sell E85 and 100 octane race gas." ! !

They still sell race gas in service stations in the U.S. ? ? ! ? ! 

I'm moving to America  !

Just out of curiosity what's it worth per litre or rather U.S. gallons ?

[joshuaho96]

4 hours ago, PLYNX said:

GohiraDave said - "Here in Las Vegas we have 91 with a few stations that sell E85 and 100 octane race gas." ! !

They still sell race gas in service stations in the U.S. ? ? ! ? ! 

I'm moving to America  !

Just out of curiosity what's it worth per litre or rather U.S. gallons ?

In my area it's something like 2.60 USD per liter for 100 octane street-legal race gas. E85 is substantially easier to find and often 30% cheaper than premium unleaded pump gas so if you can afford to convert to flex fuel instead it is much, much cheaper to run than proper 100 AKI. You can also adjust your ethanol mix to find the minimum ethanol percentage needed to balance between range and octane.

[GohiraDave]

15 hours ago, robbo_rb180 said:

The time and skill it takes to reverse engineer is hard for 98% of people that just want to plugin and go. Especially when it comes to displays and modules.
We have a guy in Australia that has finally put out a how to for unlocking the link ecu password protection.

For the OP who ever is tuning the car will recommend an ECU that they may be more comfortable/familiar with too so have a chat with them on what they use normally.
With the turbos if not aiming for big power and want the stock look have a look at high flowing current turbo's, @hyper-gear have a great reputation over here.

I will check them out. Thanks!

[GohiraDave]

13 hours ago, PLYNX said:

GohiraDave said - "Here in Las Vegas we have 91 with a few stations that sell E85 and 100 octane race gas." ! !

They still sell race gas in service stations in the U.S. ? ? ! ? ! 

I'm moving to America  !

Just out of curiosity what's it worth per litre or rather U.S. gallons ?

Yes we do! LOL. 100 is $10 a gallon or roughly $2.50 a liter. When I brought the GTR from Japan I had to use race gas because of the tune. I cried once I tuned it for 91 😄

[Murray_Calavera]

I'm amazed that there is 100 octane at the pump. Who is the target market for this fuel?

[joshuaho96]

4 hours ago, Murray_Calavera said:

I'm amazed that there is 100 octane at the pump. Who is the target market for this fuel?

Dodge Demon owners and people who have tuned their engine around 100 octane and don’t want to keep 100 gallon drums in their garage. It’s not a big market but they can charge a decent markup on it. Substantially more expensive than 100LL by a long shot. 

[r32-25t]

On 16/6/2023 at 11:18 PM, Murray_Calavera said:

I'm amazed that there is 100 octane at the pump. Who is the target market for this fuel?

Everyone, Japan don’t have pump 98ron they have 100ron. All performance cars in Japan are tuned to use it and the reason why once the cars are imported to Australia the engines blow up 

[r32-25t]

And I can tell you from experience this morning, the stuff smells like rocket fuel and you get high just from filling the car up 

[GTSBoy]

2 hours ago, r32-25t said:

All performance cars in Japan are tuned to use it and the reason why once the cars are imported to Australia the engines blow up

Well...... no. They usually run just fine on 98 without a need for a tune. When there was no 98, and 95 was the only option, that's when there was a problem.