2nd gen head and HX-35 on 1st gen???

[BWatson]

I have to apologize if some of this is common 1st gen knowledge. I am a 2nd gen'er. A good friend of mine has a 91. 5 though and I'm wondering if some of my parts would be beneficial to him or not.



My truck is a 98 12-valve. I am about to put a PDR cam in my truck and am tempted to pull the head and stud it while I have everything else apart. With the deal that PDR is having on new heads, I'm very tempted to get one of those and have it ported and 60# springs. Are there any differences between the heads on 1st gens and 2nd gens? I'm wondering if the 2nd gen heads flow any better than the 1st gens and will mine bolt right onto his engine. If so, then I'd sell my old head to him and get a brand new head. If there aren't any advantages for him though, I won't bother with it. I'd only sell it to him if it'll help him out and I could get enough money out of it to make it worth buying a new head. I'd like to be able to get at least enough money out of my current head to cover shipping cost of the new head and a new marine head gasket. Injectors are different, right? Would he need 2nd gen injectors to run this head? If so, will the connectors on the fuel lines fit 2nd gen injectors or would he need to change out fuel lines too? What about intake parts and exhaust manifold? Does all that match up?



Also, how beneficial would my hx-35 be to him? I have heard of 1st geners putting 35s on their trucks but I'm not sure if that is on pumped up engines or stock. His truck is bone stock. Without mods, would a 35 help him or not? I have a non-wg 16cm^2 housing on it now but also have my stock wg 12cm^2 still too. Which would be better for him? I am looking at getting an S-3 but only if I can unload my 35.



Since I'm on all this too... I recently upgraded from my old nv4500 and SB Con O clutch to an NV5600 and Con FE clutch. The 4500 has a full-splined main shaft and new input shaft but I broke 3rd gear that still needs replacing. He is interested in this too to get rid of his auto. I've heard he would need a special bellhousing to run a 4500 behind his 1st gen 12-valve. Is this because of the flywheel or is there something different between the cranks of the two engines? Because I pulled everything from the flywheel back from my stock setup.



He is a very good friend of mine so I'm only going to do any of this if it is a win-win situation.



Thanks in advance and again - sorry for my ignorance.

 

[Greenleaf]

Well. It's my understanding that it will fit right on there. The turbo will be a perfect fit as well. The DP flange will have to be changed if the exhaust housing is retained. The exhaust manifold and the intake, all is the same.

 

[BWatson]

That's cool that it'll bolt right up but would it be beneficial to him or are 1st and 2nd gen heads identical in flow?



I thought those 16cm^2 turbine housings could be used on both the H1C and the HX35? What's the difference in the downpipe?



Thanks for the reply.

 

[Greenleaf]

The second gen head is "supposed" to flow a tad better. Given that they are both OEM stock. Probably not much to write home about. You can perform some minor porting yourself. Pay close attention to the area around the valve guides. Smooth it up and enlarge it a tad.



The manifold as well. Match the gaskets to the flanges. Turbo flange and the exhaust port flanges. Also the exhaust housing inlet. Match that as well. I set a gasket right on each flange and go to work. Taking material off untill it is the same dimentions as the gasket.



The second gen turbo is virtually the same. However, the second gen turbo flange has a very much different design. The first gen trucks have a differnt down pipe and the DP will not bolt up. You'll have to change the exhaust housing OR remove the flange on the back end of the exhaust housing and install a differnt flange. This is given that the turbo is the OEM and not been changed out.



The OEM second gen exhaust flange is like pointed downward at 30° and the OEM first gen has no "flange". It's part of the housing. Just a lip to fasten the DP onto.



Clear as mud isn't it. I don't have pictures to show you.

 

[glhs]

The 2nd gen turbo will bolt right up and he could use his existing 1st gen downpipe. You only need to remove the cast elbow from the hx-35 and the 1st gen downpipe will bolt right on. I would use the 35-16 combo instead of the 12.

2nd gen heads are supposed to flow about 4-5% more air.

Kurt

 

[dpuckett]

I'll add my 2 cents. I'd say if it is a bone stock truck, and he plans to keep it that way, the 12cm would give him better bottom end, and with the gate pressure set to the max efficiency range of the turbo (mid 30s for the HX35), he'll get much better in town performance without choking his engine, or compromising his turbo. Now, if he tows a 30ft gooseneck stock trailer, he'd be better with the 16, as he will have better flow at higher throttle/ boost conditions. He'll also need some pump tuning and injectors.



Daniel

 

[Greenleaf]

The 2nd gen turbo will bolt right up and he could use his existing 1st gen downpipe. You only need to remove the cast elbow from the hx-35 and the 1st gen downpipe will bolt right on. I would use the 35-16 combo instead of the 12.

2nd gen heads are supposed to flow about 4-5% more air.

Kurt

The issue that I was trying to address is that when the cast albow is removed, there is nothing to attatch the DP onto. Nothing there. Just a big hole. The proper adapter is obtained from Cummins or from a turbo dealership. It's a Holset part.

 

[BWatson]

Sorry - been out of touch for awhile. Thanks for the input. I think he's going to pass on the head (not enough gain for the trouble of the work) but he is definitely intersted in the turbo now.



He's planning on leaving it stock because he is worried about the auto taking a dump. Now, if I can talk him into buying my 4500 and clutch, then he'd have plenty of "growing" room for injections and pump mods. He doesn't tow anything right now but we are into Jeepin and he plans on pulling his Cherokee on a trailer. Total weight (trailer and Jeep) won't be over 6500 pounds. Shouldn't be an issue for a stock truck and trans.



No one has responded about the 4500 though... does it take a special bellhousing to mount behind the 1st gen engine? I have the flywheel, bellhousing, South Bend Con 0 clutch, and 4500 with a full-splined main shaft out of my truck that I need to get rid of to try to recover from the 5600 swap. I thought it would be perfect for him but we are trying to figure out all the details in the swap.



Thanks a bunch guys!

 

[RBergman]

SO I am kind of in the middle of converting to the nv4500

in my 1st gen

i used the 2nd gen bellhousing

2nd gen starter

2nd gen spacer (between the engine and trans )

2nd gen clutch slave and master cylinder

 

[BWatson]

OK, so I did more digging last night on the 4500 conversion and think I have this straight now. Other than the starter, clutch hydraulics, and a pedal, the only thing he would need to swap everything over would be flywheel housing (the skinny intermediate bellhousing or what RBergman is calling the spacer)... correct? Since he'd be using my 4500 bellhousing, clutch, flywheel, yadda yadda yadda.

So, the $400 bellhousing that AA and Quad 4x4 sell, is that the complete bellhousing and intermediate bellhousing? Since he has everything else, instead of paying $400 for a bellhousing, could he just find the intermediate flywheel housing from a 2nd gen in a junkyard or someplace and just bolt everything together? I had to keep the intermediate housing when I did my trans swap so he'd need to find another one.



The blocks and cranks are essentially the same between the 1st and 2nd gens, right? So all he should need is the intermediate bellhousing. Seems simple enough but everyone makes it out to be so difficult and so expensive.

 

[RBergman]

the inermeadiate housing or space or adapter is what it will take

he will have to get a differnt transfer case or transfer case input

if he is going to use the automatics transfer case . ,

i had to move my cross member back 1 set of holes

plus he will have to fab up a t-case shifter bracket

i have some pictures of my install if you whant them

please let me know



the bellhousing that comes in the kit bolts up the getrags

spacer , plus it requires the input shaft noise cone to be

cut down

 

[BWatson]

Cool, thanks. That's what I was wondering. His is 2wd right now. His goal is to take a 2wd auto and make it a 4wd manual. I thought it was rediculous and tried to get him to just buy a 2nd Gen quad cab 4x4 with a manual but he, and his son, are attached to the 1st gen. Can't blame him, it is a cool truck.



So he'll have to look for a 29 spline 205 from a Dodge or a 241. He's leaning towards the 241 because he wants to go to driver's side pumpkin because of exhaust clearance issues with the 205 and passengerside pumpkin. I have a 3/4 ton Chebby frontend though (passenger-side) pumpkin that I was going to use to convert my Jeep to 8-lug with but decided not to so he has that axle availble to use instead of trying to find a Dodge front axle.



Is there really an issue with exhaust clearance around the pumpkin on a 4wd truck? I could see it on a 2wd but I figured there'd be enough space between on a 4wd. A 205 is going to be a lot cheaper and probably easier to find than a 241hd.



Fabricating linkages and relocating crossmember is no big deal. We design and fabricate Jeep suspensions and parts for fun. Suspension is something he still needs to decide on though. I think he's thinking leafs up front just to keep it simple but I'll probably be going to the Skyjacker D25 coils in the front of mine soon so I'll have my stock coils available. A 4-link long-arm would be really cool under that truck. He needs enough to clear 35s. He already has the tires and wheels waiting to go on. Gonna be a busy Spring.