Nikki blow through REPU w/ S5 turbo
09-18-11, 08:02 PM
#1
Nikki blow through REPU w/ S5 turbo
I recently found out I'm going Nikki blow through with an S5 turbo in my REPU. I really like this guy's exhaust manifold.* I'll have to do the same thing as there is no way the stock mani will fit the engine bay and intake manifold.
*added link to picture
I decided that ports that close at the same time as a T2 are what's best for all around use. The intake ports are all 74 spec so the primaries technically are bigger than stock T2 primaries, but secondaries are the same. As for exhaust ports, I've got GSL-SE open/close timing so they open later than T2, but close exactly the same. This gives it a little bit of lip for some anti-reversion properties (so awesome!) compared to if I'd ported them out to T2 opening spec as the GSL-SE size sleeves are smaller than T2. Kinda smart of me in retrospect as the engine is already together and currently has a Camden 5" supercharger on it. The Camden will go onto a more deserving engine (one whose GSL-SE ports have already been ported to T2 spec, d'oh!).
I'll begin modding the truck's exhaust some time this week and pulling the Camden. More details to follow...
*added link to picture
I decided that ports that close at the same time as a T2 are what's best for all around use. The intake ports are all 74 spec so the primaries technically are bigger than stock T2 primaries, but secondaries are the same. As for exhaust ports, I've got GSL-SE open/close timing so they open later than T2, but close exactly the same. This gives it a little bit of lip for some anti-reversion properties (so awesome!) compared to if I'd ported them out to T2 opening spec as the GSL-SE size sleeves are smaller than T2. Kinda smart of me in retrospect as the engine is already together and currently has a Camden 5" supercharger on it. The Camden will go onto a more deserving engine (one whose GSL-SE ports have already been ported to T2 spec, d'oh!).
I'll begin modding the truck's exhaust some time this week and pulling the Camden. More details to follow...
09-19-11, 12:27 PM
#6
Here's the truck. Sorry I didn't get these up yesterday.
Ready for a new engine!
New engine going in. Note the recolored bellhousing (silver looks about a hundred times better)
Close up of the interesting exhaust ports. They're GSL-SE size but due to the smaller sleeves, I couldn't port them as big as T2 because then I'd lose the masterful lip which helps reduce reversion! Thanks j9fd3s for that tidbit of information. Intake ports are '74 spec. Should match the S5 turbo pretty well.
Ready for a new engine!
New engine going in. Note the recolored bellhousing (silver looks about a hundred times better)
Close up of the interesting exhaust ports. They're GSL-SE size but due to the smaller sleeves, I couldn't port them as big as T2 because then I'd lose the masterful lip which helps reduce reversion! Thanks j9fd3s for that tidbit of information. Intake ports are '74 spec. Should match the S5 turbo pretty well.
09-20-11, 12:53 AM
#7
Just a mini update. I prepped a used RB header flange so I can reuse it and build a road race header clone for a friend's REPU. Since the exhaust center section on mine is still installed, all I gotta do it pull the SC (was going to do that anyway), pull the header and throw in the two flanges and a couple of pre-bent pipes from an RB dissassembled header kit. Then weld and paint it with high temp paint for rust protection. What a fun day I'll have tomorrow.
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09-21-11, 12:56 AM
#11
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Nice!keep the pix coming.unfortunately i've been computerless for a good amount of time now or i would have posted plenty of updated pix in my repu build aslo....
09-24-11, 09:55 PM
#12
Sorry I haven't updated in a while. I got busy on two other builds. Now I'm back to the REPU. I came up with a budget to get started. Decided it's best to ditch the S4 NA assembly and go with an R5 assembly. Why? Nice low mileage factory balanced assembly, 9.2 compression ratio, new Atkins 3mm apex seals, NF01 corner springs, competition outer oil springs, new Atkins Viton o-rings, freshly resurfaced GSL-SE flywheel, NOS S4 waterpump impeller; will have to swap the NA waterpump housing to a turbo model when I get the turbo = I get both together in a package deal but for now the NA is fine. I also get a rising rate or boost referenced fuel pressure reg but for now a Holley 1 to 4 psi is good enough. Also an in-car fuel pressure gauge that reads up to 15 psi with a safety remote sender thing. PercentSevenC knows what they're called. Anyway all this is going to cost me to get started is $114 for a gasket set lol. Oh and a set of Viton o-rings I suppose. Really not a bad way to go for the peace of mind. 3mm and 9.2 CR. 
It's a truck so I can get away with the heavy R5 rotating assembly. This frees up the nice light S4 NA assmembly for something else...
Question: should I do anything with the ports? 74 spec intakes and GSL-SE spec exhaust. I think that's perfect but it's not exactly T2 spec, ie where the turbo came from. Not a big deal?
It's a truck so I can get away with the heavy R5 rotating assembly. This frees up the nice light S4 NA assmembly for something else...
Question: should I do anything with the ports? 74 spec intakes and GSL-SE spec exhaust. I think that's perfect but it's not exactly T2 spec, ie where the turbo came from. Not a big deal?
09-26-11, 07:15 PM
#13
Mini update: Ah screw it. I'll stick with the S4 NA assembly in the truck. After budgeting everything it makes more sense to leave it alone. It also makes sense that at low RPM/off boost conditions, the slightly higher comp rotors will make more power. This is actually a good thing in a truck, where you'll be towing stuff which while at a high load might not be at high RPM. Makes sense. It's not an RPM-dependant supercharger. It's also way cheaper and less time consuming to leave it all in the truck as is. I'm running out of warm weather up here so I gotta get things done this fall as quick as I can.
I'll keep updating as things develop.
I'll keep updating as things develop.
09-28-11, 12:51 AM
#14
Here is the turbo I'll be using. It's still in use with the Weber seen in the pic, but I'll get it at some point.
I bet the Nikki will drive a full cart of apples better than the DCOE did. Maybe not as much peak power but it's a truck; you want it to drive as such. Not a herky jerky pony jockey.
I bet the Nikki will drive a full cart of apples better than the DCOE did. Maybe not as much peak power but it's a truck; you want it to drive as such. Not a herky jerky pony jockey.
09-28-11, 02:07 PM
#16
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That pic was from when we were test-fitting it to figure out how thick of a spacer it needed to clear the LIM. We could only get away with doing it that way because it was a sidedraft manifold. If it were a stock or downdraft manifold, we'd have had to make an Aaron Cake spacer, which would have been awkward because of the position of the idler arm.
09-28-11, 02:17 PM
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You are correct, sir.
That pic was from when we were test-fitting it to figure out how thick of a spacer it needed to clear the LIM. We could only get away with doing it that way because it was a sidedraft manifold. If it were a stock or downdraft manifold, we'd have had to make an Aaron Cake spacer, which would have been awkward because of the position of the idler arm.
That pic was from when we were test-fitting it to figure out how thick of a spacer it needed to clear the LIM. We could only get away with doing it that way because it was a sidedraft manifold. If it were a stock or downdraft manifold, we'd have had to make an Aaron Cake spacer, which would have been awkward because of the position of the idler arm.
Looking forward to more updates!
Last edited by REPU_74; 09-28-11 at 02:19 PM.
12-06-12, 07:21 PM
#23
I know you especially were looking forward to this build. Um, if you'd like me to go ahead with it, I will. But I'll need a lot of help from those who know turbos. Sorry to be so wishy-washy. I just have no experience with turbos and feel like betting on a sure thing anymore, like NA, but I know deep down I'll probably always be wanting more power. :/
First off, I'll list some features the current setup has and we'll go from there.
Long primary NA exhaust that's quiet and flows well. But the plan was to throw it in another REPU. Thus making room for a new 3" turbo exhaust system - have most of the components already such as two magnaflow 4x9 ovals and was going to get an RB universal 3" presilencer. The 3" flanges and gaskets are here too.
Big Carter 110gph fuel pump currently installed. Also have a new Walbro 255lph and a good used Mallory boost referenced fpr sitting here. Just need to redo some fuel hardlines to make an adequate return style fuel system. It's kind of involved and I'll need to drop the tank. I wasn't looking forward to it. I may also need a swirl pot as there is no sump cup or baffling as far as I know. Is turbo worth my time and energy if all this extra stuff needs to be done? Or is NA best? Well for now NA is best, but I know I'll always wonder "what if?". ;/ (that's the unsure smilie.)
Engine consists of:
74 ported medium strength R5 side plates (all three are genuine late model J-spec nitrided R5) with 17 tension bolts and a narrow curved rib at the oil filter pedestal dowel pin area. I suspect this type of plate will handle up to 300HP without failing as it is a stronger casting than your typical Y plate from a 1st gen. I read some posts recently where a guy said he kept splitting rear irons at 300 in his blow through 1st gen using Y plates, so that's where my assumption came from. Your thoughts please?
The plan was to swap in a strong R5 rear plate with a thick rib (like any JC Cosmo or S5 rear plate) which has 18 tension bolts. However I'm in the process of planning out a turbo build in my GSL-SE, so it's going there, along with an *FD rotating assembly an S5 NA flywheel. This will be my big turbo build and the REPU was gonna be my big NA build. But if you can help me out, you may yet see a turbo REPU.
*The FD rotating assembly and hardened stationary gears were going to go into the REPU but not anymore. I recently tore down an FD core that looks ok. I also have a resurfaced S5 NA flywheel to stay compatible with my old school ribcase 5 speed in the REPU. No plans to upgrade to a T2 tranny. But now this setup can go in the GSL-SE which has an S5 NA tranny. Arron Cake said these break no matter what at 400HP so I don't plan to go that high.
The REPU's pressure plate and clutch would have slipped under boost I'm sure. 225mm centerforce pressure plate and a stock duty Daikin disc (with rubber springs before they changed the name to Exedy and went to steel springs with a better design). I chose this combo because it drives fantastically. No desire to swap to a street strip pressure plate, but I may go for a stronger disc. I'm not too confident in the stocker's ability to handle the demands of the chassis, but it does drive nice! Maybe an ACT street disc? A little abrupt engagement is ok.
My J-spec R5 rotor housings have GSL-SE port timing and sleeves. I would have ported these out to T2 spec to better drive the turbo. But this is not necessary if staying NA. And the GSL-SE timing lends itself better to low end torque!
The current REPU rotating assembly is S4 NA with a matching NA flywheel. This combo feels right in a vehicle this heavy with the tall 77 rear diff gearing it has (3.9!!) for some reason. I don't wish to lighten the flywheel much more than it is. S4 NA is 24 pounds. As you know the S5 NA is 21 pounds so a bit more appropriate in a GSL-SE but less so in a REPU.
I once tested this truck with an RB light steel flywheel and an R5 assembly. It was too light at launch but as soon as you're moving it was fine. Not interested in another light steel flywheel.
The turbo I planned to use has these features:
cold side 60 A/R
70.00mm/54.14mm
hot side AR 1.15
73.45mm/63.15mm
T4 divided exhaust housing
The exhaust A/R is kinda big I know, but it was cheap and should work well to spool the small compressor wheel fast like a stock S5 NA! I think I would need to port the exhaust out to T2 spec to drive it well, though.
I have this little turbo sitting here ready to go in something. REPU? GSL-SE? Other?
When I decided to go NA in the REPU I decided I'd throw this small turbo in the GSL-SE. However now that I think about it, if the GSL-SE is supposed to be my big turbo project, perhaps the REPU could be a lesser turbo project. Then this small turbo could go in the REPU and I could look for something more appropriate for the big turbo project in the 7, like a GT35 with of course a divided T4 exhaust housing and like a .84 or 1.00 AR so it has a chance at spooling well and wowing me (important).
Oh man I'm feeling less than confident about turboing the REPU, but like I said if you guys are willing to help out, I'll go for it!
One last question. The REPU currently has S4 NA rotors. I've been told these are excellent at fast spooling turbos due to their 9.4 compression ratio, however you are severly limited to how much boost you can run. I wasn't planning on much more than um like uh 7 or 10 I think? Here I go again shoing how little I know about this subject. What boost should I run? And if I can fit a small intercooler, how much more could boost I run?
Carbs available:
•boost prepped Holley 650 double pumper (I know nothing about holleys so I'll need your help!)
•84-85 Nikki which can be boost prepped easy enough (I know how to work on these, at least)
First off, I'll list some features the current setup has and we'll go from there.
Long primary NA exhaust that's quiet and flows well. But the plan was to throw it in another REPU. Thus making room for a new 3" turbo exhaust system - have most of the components already such as two magnaflow 4x9 ovals and was going to get an RB universal 3" presilencer. The 3" flanges and gaskets are here too.
Big Carter 110gph fuel pump currently installed. Also have a new Walbro 255lph and a good used Mallory boost referenced fpr sitting here. Just need to redo some fuel hardlines to make an adequate return style fuel system. It's kind of involved and I'll need to drop the tank. I wasn't looking forward to it. I may also need a swirl pot as there is no sump cup or baffling as far as I know. Is turbo worth my time and energy if all this extra stuff needs to be done? Or is NA best? Well for now NA is best, but I know I'll always wonder "what if?". ;/ (that's the unsure smilie.)
Engine consists of:
74 ported medium strength R5 side plates (all three are genuine late model J-spec nitrided R5) with 17 tension bolts and a narrow curved rib at the oil filter pedestal dowel pin area. I suspect this type of plate will handle up to 300HP without failing as it is a stronger casting than your typical Y plate from a 1st gen. I read some posts recently where a guy said he kept splitting rear irons at 300 in his blow through 1st gen using Y plates, so that's where my assumption came from. Your thoughts please?
The plan was to swap in a strong R5 rear plate with a thick rib (like any JC Cosmo or S5 rear plate) which has 18 tension bolts. However I'm in the process of planning out a turbo build in my GSL-SE, so it's going there, along with an *FD rotating assembly an S5 NA flywheel. This will be my big turbo build and the REPU was gonna be my big NA build. But if you can help me out, you may yet see a turbo REPU.
*The FD rotating assembly and hardened stationary gears were going to go into the REPU but not anymore. I recently tore down an FD core that looks ok. I also have a resurfaced S5 NA flywheel to stay compatible with my old school ribcase 5 speed in the REPU. No plans to upgrade to a T2 tranny. But now this setup can go in the GSL-SE which has an S5 NA tranny.
Arron Cake said these break no matter what at 400HP so I don't plan to go that high.The REPU's pressure plate and clutch would have slipped under boost I'm sure. 225mm centerforce pressure plate and a stock duty Daikin disc (with rubber springs before they changed the name to Exedy and went to steel springs with a better design). I chose this combo because it drives fantastically. No desire to swap to a street strip pressure plate, but I may go for a stronger disc. I'm not too confident in the stocker's ability to handle the demands of the chassis, but it does drive nice! Maybe an ACT street disc? A little abrupt engagement is ok.
My J-spec R5 rotor housings have GSL-SE port timing and sleeves. I would have ported these out to T2 spec to better drive the turbo. But this is not necessary if staying NA. And the GSL-SE timing lends itself better to low end torque!
The current REPU rotating assembly is S4 NA with a matching NA flywheel. This combo feels right in a vehicle this heavy with the tall 77 rear diff gearing it has (3.9!!) for some reason. I don't wish to lighten the flywheel much more than it is. S4 NA is 24 pounds. As you know the S5 NA is 21 pounds so a bit more appropriate in a GSL-SE but less so in a REPU.
I once tested this truck with an RB light steel flywheel and an R5 assembly. It was too light at launch but as soon as you're moving it was fine. Not interested in another light steel flywheel.
The turbo I planned to use has these features:
cold side 60 A/R
70.00mm/54.14mm
hot side AR 1.15
73.45mm/63.15mm
T4 divided exhaust housing
The exhaust A/R is kinda big I know, but it was cheap and should work well to spool the small compressor wheel fast like a stock S5 NA! I think I would need to port the exhaust out to T2 spec to drive it well, though.
I have this little turbo sitting here ready to go in something. REPU? GSL-SE? Other?
When I decided to go NA in the REPU I decided I'd throw this small turbo in the GSL-SE. However now that I think about it, if the GSL-SE is supposed to be my big turbo project, perhaps the REPU could be a lesser turbo project. Then this small turbo could go in the REPU and I could look for something more appropriate for the big turbo project in the 7, like a GT35 with of course a divided T4 exhaust housing and like a .84 or 1.00 AR so it has a chance at spooling well and wowing me (important).
Oh man I'm feeling less than confident about turboing the REPU, but like I said if you guys are willing to help out, I'll go for it!
One last question. The REPU currently has S4 NA rotors. I've been told these are excellent at fast spooling turbos due to their 9.4 compression ratio, however you are severly limited to how much boost you can run. I wasn't planning on much more than um like uh 7 or 10 I think? Here I go again shoing how little I know about this subject. What boost should I run? And if I can fit a small intercooler, how much more could boost I run?
Carbs available:
•boost prepped Holley 650 double pumper (I know nothing about holleys so I'll need your help!)
•84-85 Nikki which can be boost prepped easy enough (I know how to work on these, at least)
