Dale FZ1

Now there is more information not initially provided. Split pulse housing. What manifold are you using? Pictures too please.

+1 for further checking of the turbo and/or replacing it with a known good unit. The plot on post #10 is interesting. That setup holds 19psi but power flattens and it's basically holding 350hp from 4250-5250rpm before tapering. I'd be looking at that as a fair indication that the compressor really can't efficiently push more air. 400hp on E85 from a 30DET at 19psi is not what I'd consider outstanding results, although this spec looks like it would be quite good on the road.

Daniel from your initial post about the "supposed" turbo spec: Have you had the housings off to inspect and/or measure? What engine does this particular HX35 spec get fitted to, and at what power rating? The boost curve indicates the thing gets up and boogies nicely down low but it's falling from 4200rpm onwards. That's 1000 engine rpm through which it is delivering max boost. Presuming the engine setup is all correct, and your search for boost leaks appears thorough. Looking like a restriction or flow efficiency issue with the turbo system. eg. no stray rag in the intercooler, pipe work not nasty, and it may be a big presumption that you have a 12cm housing simply because of what might be a part number. To me it looks like what you'd expect with (just picking a number) an 8cm housing on those quoted impeller sizes. (Not likely because your unit would have come from a diesel with focus on turbine flow efficiency). Probably little to no chance of getting a different turbine housing to try, so is there any other variant of the HX35 you can get onto for cheap if nothing becomes evident? You've got a head-scratcher there, and some of the suggestions seem basic, but when identifying cause of problems I tend to start with the basics.

Failing to understand necessary clearances and then check that they are within those parameters during preparation and assembly. Talking bearing clearances, piston to bore clearances, and ring end-gaps. Secondly, failing to adhere to absolute cleanliness and eliminating dirt, sludge, machine filings etc from galleries and other nooks/crannies. This is prior to assembly, up until the engine is effectively completed/sealed. Thirdly, using too much liquid gasket and having it lumps find their way to the sump then causing oil starvation.

How does it hold a line on a long/tight radius turn, and what's happening with tyre wear on the outside front shoulder at 3 degrees?

As a matter of interest, what front camber does your car run, and any idea how much bump travel you use?

^^ +1. Cage looking pretty good. Hip bars look a little high - finishing closer to armpit level?? What's it like for ease of entry and exit from the driver's seat?

RB = Race Bred. You could always put a few John Deere stickers about the place if it sounds a bit agricultural?

It's a path I'm heading down. Simple is good. Provided it doesn't hunt really badly and stall.

It might be worth a trial run to delete the valve altogether. See if it can idle reasonably stable without the clutter. Race car. No a/c and presuming it's not being run with electrical loads from headlights etc.

I'd like to see more detailed pics of what you have done underneath the front end to fit up the undertray/splitter. eg. is the OEM plastic "splash guard" still in place or deleted? Strongly suspecting that some mod around the engine bay has upset airflow. It may be that the OEM radiator is not the culprit for your cooling issues. Otherwise the in-car shows you're having fun with a simple enough package.

Requirement for a Sainz bar is only for certain event classification. If it's only club level event, not mandatory. I can always install one in the future if required. Sainz bar effectively prevents the windscreen coming down in the case of a heavy roll (think back to Carlos Sainz rolling his car at Rally WA in the early 90s). They do make entry/exit from the car much more tricky, so that in itself becomes an issue. My concerns in a track crash scenario is more frontal and side/angle impacts so the bracing I used reflects that. Personal preference. Juggling return on construction/design effort, I'd suggest a brace between the front towers is easy. Tie bars running forward from the A pillar legs really needs a bare shell construction simply because there's very little room to work with. They might do something good, but the Skyline shell is a very much stiffer base structure than a Datsun 1600 or early Z which seemed to get a lot of benefit from similar bar work. So for an R chassis I think it's not as worthwhile. The issue might be whether it's allowable in the event type(s) you want to run in.

There's pics of my cage and the parcel shelf work etc in a thread under Motorsport Builds. If there are particular events you are targeting, I'd strongly recommend looking at their regs because there might be limits on what cage design elements are acceptable. Otherwise be a bit creative but don't add weight unnecessarily. Getting the front shock towers and A pillars/firewall area tied into the cage design would have to pay dividends for overall rigidity but there looks to be a lot of work for questionable improvements to performance or safety. You'd very likely find yourself running something like a floor mounted pedal box, some sort of custom dash and race instrument pod, and push the driver rearwards (a good idea) while you're at it Budget has to influence proceedings somewhere. There were some pics floating about on this forum of a cage using those design elements but never saw it as a finished unit. I think the bloke involved in building it has disappeared off the scene.

Door trims look great Neil. Michael did a great job. You can't leave them raw aluminium; shows up the little scratches that will happen easily. I'm going with powder coating on mine. Simple, hard, durable, cheap. Carbon wrap would look good if you've got it in other areas.

My R33 had the rear parcel shelf sheet metal removed before caging. Couldn't see the point in running the cage to the rear tubs when the shock towers could be used once thing were tidied up a bit. Word of caution: remember the fuel tank is in close proximity to where you will presumably be drilling out some spot welds associated with that parcel shelf bracing, and welding other stuff in. It could be time well spent to remove the tank. Safer, and you can access other stuff much more easily while doing your mods.

Checking my setup notes the caster was actually 9 degrees. Pays to not rely solely on recall. Hard Race radius rods.

Change is as simple as turning a spanner and try again. Caster figure is about as far as I want to go; inner guards have seen some adjustments via hammer to give clearance to tyres on lock and with suspension at full bump travel.

Rubber is Hankook Z221. Cold pressures 29F, 27R. It achieves 5-6 psi pressure rise during a 3-4 lap sprint. Front left is the hardest working tyre, and it rises the most. Caster 11 degrees. Front anti roll bar 24mm adjustable. I have done/do temp spot tests across the face of the tyre, but tyre wear is the more reliable measure of what is going on. Temps are going to change during the cool down/in lap. I'm going on advice from a very well credentialed suspension engineer with regards to what changes to trial. The aim is for least amount of changes for best return on effort, and 3.5-4 degrees of camber was felt to be a good starting point. It hasn't proved to be enough, so we are winding in a bit more to assess. With luck and a lot of effort/organisation we will take it out for a test session prior to the next event in April, and should be able to form an opinion about what's working or what's not.

^^ above comments are a bit of a blind alley. OP wants to know about the response capability of his turbo. Andrew the spec you are running is broadly equivalent to a Garrett GT3576 in terms of impeller sizing and ballpark airflow capacity if not response/cost/durability. If it is an internally wastegated setup then it is possible your response may not be optimal compared to a reasonably well configured manifold/external gate. Your figures are a bit rubbery to comment on, although the power figure of 320rwkW on petrol and 20psi is quite respectable (compares ok to a GT35 too). On an RB25 with that turbo, if you made 20psi at 4000rpm you should be quite happy. If it takes until 4500rpm it's still not crappy but you'd hope for better. However it is not a bottom-end response type turbo and I wouldn't expect much action under 3000. But it should be very strong across 4000-7500 or higher depending on the camshafts you've got. If there is an 8cm housing available it's likely to choke the thing up high, with maybe a 3-400rpm earlier spool. Not really a win-win, Check out a TDO6SL2-20G 10cm, or the Hypergear version with their "20.5G" compressor. Sticking one of those on; fuelling with E85 should give about the same max power figure with a whole lot better bottom end response.

Pic shows a head and cams already installed on the bottom end??

PM sent with pics. Have a look inside the throat of the turbine housing, wipe away soot with a rag if you need to. There may be a number cast inside. If it is what you believe it to be, the number should be 82. If not, it may be 106. There is a visible difference between the two units when you see them side by side; a 1.06 is a much fatter snail. Uneducated opinion, yours looks like a 0.82. It's making the numbers up top, what does the boost curve look like?

Standard cams? Either way, get them set correctly for timing by someone who knows how. Don't go off the timing marks and expect they will be in the correct position.

Pretty stout figure there. What fuel are you running? And was there any result with the search for carbon boot and the lexan side/rear window replacements?

Sprint events are the primary interest, and what it's been doing. I'd also like to give hillclimb a go. The general costs associated with circuit racing don't make that discipline attractive. The issue of what category fits a mildly modified 2wd R33 is something that keeps a lid on that idea.

Time for a bit more suspension work. Fairly heavy tyre wear on the front outer shoulders combined with a fair bit of mid corner understeer indicated that -4 deg camber is insufficient. A few LCA modifications should see us with a range of 5-6 degrees. Pics to come when it's reassembled and on the ground. Rear cradle out while I inspect the tank to deal with some sort of fuel leak, and I have installed solid alloy bushes. Will confirm that removing the OEM bushes takes a fair amount of effort. I just smashed out the rubber guts with wood chisel and then used an airsaw + cold chisel to collapse the steel shell and remove it from the cradle tube. Resisted the urgings from Nigel to set fire to the rubber. Dressed up the cradle tubes where I had left small marks, then a good smear of anti seize. Chilled the new bushes down in the freezer, then used a UNF bolt to pull them into the tubes. Took a day to remove old stuff and prep for the install, and about an hour to install all 6 new ones.