Holset HX35 on my SR20.....

[UGOT8UP]

Thanx for your follow up SR20 guy . I always like to see someones direct comparison impression of any turbo. Afterall in the end, we do all this work for how it feels.



What! get moving! I need something to swap to after I max out the big h1c.

What the hell man you don't have that thing MAXED yet? You better get in gear, Monday should be the ship date

 

[SR20drag]

Correct, that's look like the fittings they sell for the compressor housings to increase the boost for the trucks
Can you give us insight as to what rpm its spooling for you,etc?

I'm currently boosting at 18psi and it hits full spool somewhere between 4200-4500rpm. That is from a 3rd gear pull under a load. I cut my fuel pressure back down to 43.5psi base pressure. I forgot I had it up to 52psi base with the onld GT2871R. My afr's are still 10.8-11.2 range. It was in the low 10's at WOT with the higher fuel pressure and 15psi. The HX35 feels like it won't feel at home with anything less than 25psi. I will be installing my intake and making a couple of passes in the 1/8th this weekend before I go to the dyno next Thursday. I had to push my dyno back to get the intake on.

 

[SR20drag]

I've only put about 250-300 miles on the turbo and I'm already starting to get a little shaft play and I am going to have it rebuilt before I go any further and take it to the dyno and push it north of 25psi. It was obviously run at it's max on the truck that it came off of with that restrictor on the pressure feed and I bought it from DK diesel(a performance diesel shop in Washington) so I'm sure it was pushed to it's limits. I only have $250 in it but Tim's Turbo and my local turbo shop both want $350-$400(is that to high?) to rebuild it and I'm looking for some other options. DSM-onster, I've seen a guy in the turbo tech threads that rebuilds them and seems to do a stand up job. Any help on a trust worthy rebuilder that won't have my car down for a month would be great??

 

[kottyking]

Yep there is a member here that is great at rebuilding turbos. Jusmx141. Shoot him a PM.

 

[SR20drag]

After reading the HX35 oiling thread I think I need a restrictor in my line. I have a 12mm banjo to -4an adapter on my stock oil feed location going to a -4an line into a regular earls 12mm/-4an fitting from summit racing. I hold about 20psi at idle and about 75-80psi at high rpm. I don't want to have it rebuilt and then blow it again!

 

[SR20drag]

Yep there is a member here that is great at rebuilding turbos. Jusmx141. Shoot him a PM.

Thanks for the hookup. He is taking care of my turbo as we speak. I plan to be on the dyno next Friday if everything goes well.

One question.....

I don't have water/alky injection and will be pushing my injectors to there limits with the HX35. Would you tune it for strait 110 race gas on high boost or would you consider a 80/20% 93 and E85 mix. All I've ever ran is strait 93 octane and I'm trying to squeeze everything I can out of my setup. I have some serious racing coming up in the next 3 weeks and I want my car in the 7.20@96-100mph range at the local 1/8th mile track. I ran consistant 7.6's@93 with my old 345whp Gt2871R setup with stock cams and intake on 93 octane. Surely my goal can be achieved with the HX35, tomie cams, and a high flow shorty intake.

 

[dsm-onster]

You don't want to run an alcohol mix if you're trying to get the most out of your injectors. The reason is that alcohol requires a lower a/f ratio to achieve stoich and peak torque. IOW, when tuning for a certain lambda on your wideband, to maintain that lambda or even to run it leaner to stoich, you will need MORE fuel. General ideal a/f ratio for gasoline is 12:1. For E98 it is 8:1. For a mix anywhere lower than 12:1. You should definately run race gas or water injection and pumpgas to get the most out of injectors.

 

[SR20drag]

Thanks Matt. I will keep you posted on how my dyno and track times come out in the next few weeks.

 

[dsm-onster]

Please do!

 

[SR20drag]

Here it is at 23-24psi on 110 race gas. I just don't think the 2.5" DP, log mani, and 12cm2 housing is flowing enough. I think I could get these numbers at 18-20psi with a BEP .70ar, 3" DP, and a custome tubular mani.

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By the way, it makes very little boost in first but spools just as fast as my GT2871R or faster in 3rd and 4th. I'm trapping 95-96mph in the 1/8th at 24psi but it is very hard to launch without the 2 step. It barely opens the gate before 7500rpm in 1st but is at full boost by 4500 in 4th. Is it all in the mani, housing, and DP, or is there something else I can do to get it going in 1st. I love the setup except for 1st gear and it's killing me.

 

[dsm-onster]

That log manifold may not be helping you at this point. That's for sure. But it is still odd that your 1st gear is laggier than with another turbo, but your 3rd-4th sees boost faster than another turbo. Load is load. You have the same load when in the same gear. Have you done any lightening of the car when doing the turbo swap?

I would definately try upgrading the down pipe to 3" first. Before going to another turbine housing. An it's not helping with that angle off the turbine housing. I would get a 2.5" to 3" reducer and a mandrel bend 45 3" pipe to start off your 3" down pipe insted of angling at a 45 with a straight pipe right off of the turbine housing like that. If you have exhaust, is the rest of your exhaust 3"? Do you have your wastegate orientation different in this setup? Is it recirculated? And if so, is it recirculated in the same location?

Didn't you mention that it definately spools faster than you gt28? That was before the rebuild right? Was the turbo assembly balanced?

Honestly, a taller rear gives you more load and speeds the spool. The old 280zx platform comes to mind. The turbo rears are taller (lower gear tooth count) than the non-turbo rears. You might do better to go back to the stock rear. The galant VR4 1st gear is taller than the dsm 1st gear. And if it doesn't break, it's nice because you get boost earlier in 1st. That's why so many guys like going to the taller evo 1st gear in our platform. It's stronger and taller netting a faster 1st gear spool speed.

The gt28 has a much smaller turbine wheel than the hx35. You have a 600hp turbo there with that compressor and big turbine housing. It's a wonder the spool is the same or better in 3rd and 4th. The 7blade hx35 compressor is proving to be slightly more laggy than the lower flowing 8blade.

 

[SR20drag]

I switched my rear diff to a 4.36 from a 3.91 thinking it would help but it killed my spool in first. It spools maybe 300rpm later in 3rd and 4th then the 2871 according to the dyno plots, but still feels good. I'm going to switch back to the 3.91 gear and I would like to trade my HX for HY if you know anyone intrested. I am keeping my tune and 72lb injectors so I feel that the HY35 will max it out with much quicker spool with the non divided 9cm2 housing. I'm having a custom tubulat mani built and then going with a 3" DP when I have room around my brake MC. Do you think the HY35 will make 400+ on my current setup and with how much faster spool?

 

[SR20drag]

I have a open dump tube and my 2.5" is only about 12-15" long and it goes into my old 3" TBE. I want a HY35 or a .55ar T3 housing on my HX, if they make them. I should still be able to max out my tune and spool much quicker. Right now I've got a 600whp capable turbo on 72lb injectors and a rom tune that's only good for 430-440whp max. I've seen HY35's make that on honda's at 25psi. Anyone want to trade a HY35 for a freshly rebuilt HX35(7 blade)???

 

[SR20drag]

Sold my HX35 to Justin and bought a GT3076R used for $500 with no turbine housing. I'm ordering a .63 ar 4 bolt GT housing and a DP flange and should have it running by next weekend. I am also having a custom tubular mani built that copies the full race mani to better position the turbo for a 3" DP.