Advice needed on chassis strengthening | The Z Club of Great Britain
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Advice needed on chassis strengthening

Discussion in 'Rebuilds and restorations' started by TheHulkGB, Oct 29, 2019.

  1. TheHulkGB

    TheHulkGB
    Z Club Member

    Hi guys,
    My 260z has gone in for restoration today and it’s eventually going to be a RB’d car. The plan is to run around 6-800hp so I’d like some advice from some of the more experienced members on what needs to be done to the car chassis/body to strengthen it?
    Any and all help is much appreciated
     
  2. SacCyclone

    SacCyclone
    Z Club Member

    Every seam on my car was stitch welded for strength and rigidity. The full cage helps too but not really practical for street use. Mike
    IMG_0092.jpg IMG_2734.jpg IMG_0794.jpg
    IMG_0795.jpg
     
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  3. Ian

    Ian
    Z Club Member

    Seam weld main areas, imo avoid the very front, makes it harder to repair should you get a knock, I've only gone as far as the radiator panel.

    Extend floor rails to join up with rear frame

    Weld in bar beetween rear struts if you are not going for a cage.

    Add a bar from the front of the rocker connecting up to the underneath of the outer front wing box frame.



    I'd also say you will be better keeping to the 450-550hp range for an S30 and aim for drive-ability and low turbo threshold over power. On most of the Zs I've seen with big power they can't put it down, it becomes unusable until 4th gear and you aren't actually any faster (and possibly slower) in terms of acceleration than one with less power. Trust me, 500hp in an S30 does not in anyway feel slow. Mine can do 100mph in under 7.5 seconds.

    If however you want to go for 800hp I'd 100% say get a full custom weld in cage that ties into the front strut towers.
     
    Last edited: Oct 30, 2019
  4. TheHulkGB

    TheHulkGB
    Z Club Member

    Thank you for the detailed reply guys, is there any advantage to stitch weld over seem welding?
     
  5. datsfun

    datsfun
    Z Club Member

    What is the intended use of the car ? Fast road, drift, completion, straight line duties ?
     
  6. TheHulkGB

    TheHulkGB
    Z Club Member

    Fast road and maybe some 1/4 mile drags
     
  7. Ian

    Ian
    Z Club Member

    In fabrication seam welding means a continuous weld along the entire join however usually when people say stitch welding and seam welding they mean the same thing if referring to a chassis. As in you are welding stitches along the seams, usually 1 inch stitches 1 inch apart, this is what I would go with, other options are 1 inch weld 1.5" apart and some go for just a spot of weld but a lot more of them like a spot every 15mm apart.
     
  8. datsfun

    datsfun
    Z Club Member

    Based on what I have read , 4-450bhp would be sufficient. Any more and you will most likely struggle to put the power down or turbo lag / power curve will make it an on and off car ...

    The 1JZ car owned by a forum member here is an excellent example of a super quick car which is finely balanced in virtually all departments.

    I would do alot of research before spending heaps on chasing BHP that will not proportionately improve your track/quartermile times

    My 10p worth:smoke:
     
  9. TheHulkGB

    TheHulkGB
    Z Club Member

    Thanks for making that clear, stitch weld it is then
     
  10. TheHulkGB

    TheHulkGB
    Z Club Member

    Thanks, I’m open to all the advise I can get. Might cap the power at around 600 then
    If turbo lag is your concern then I could always go TT or I’ve got my eye on the new Garret GTX3584RS which is faster spooling. Would those choices make you change your mind? Also my consider TC and boost by gear.
     
  11. johnymd

    johnymd
    Z Club Member

    I run a 1jz in my blue and haver done since 2010. It has evolved a lot over the years. Initially the improvements were positive but as of late they were for the worse. I started with a standard-ish car and a factory 1jz (320hp) and the extra power was great but soon realised I needed brakes/ suspension and cage to suit. After all these mods I looked for a bit more power and with minor changes I got the power up to 380hp plus an extra 70hp of nitrous for the strip. The car became perfect at this sort of power and you could fully utilise all of it on the road or track. This was enough power to get me down the strip in 11.1s@132.5mph. From then on and my quest for a 10s run it all went pair shaped. I went after market ECU, bigger injectors, single GT35 turbo, uprated clutch, and the power went up to around 490hp and my drag time went down due to the drivability and failure to use all the power. Car has now sat for over a year as I got fed up with it. I am only now planning its return for next year and first part to replace is the turbo. I will be aiming for 450-500hp but with much more torque at the low end so the choice of turbo will be either a GTX3076r .86/.64 of the new G25-550/660.

    This is all just IMO and the route that I think is good for my needs.

    PS. I a Life Racing F88 so launch control, boost by gear, traction control and torque reduction will all be implemented (some already are).
     
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  12. Albrecht

    Albrecht Well-Known Forum User

    800BHP chassis rail delivery:

    rsj-delivery-6m.jpg
     
  13. ben240z

    ben240z
    Z Club Member

    You can be soooooooo helpful without people even knowing it. At least this will double up as a jacking point..

    On topic though I think you need to have an understanding of where the stresses and loads go in a bodyshell and how you can distribute those loads. Then you will be able to add the strength needed in the right places.

    Good luck with the build and look forward to seeing it develop.
     
  14. ben240z

    ben240z
    Z Club Member

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  15. johnymd

    johnymd
    Z Club Member

    I was thinking just the same about that dolly.
     
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  16. Ian

    Ian
    Z Club Member

    Thats 3 people including me that have now recommended not chasing too much power, trust us, it will 100% drive better with around 500hp. I think the most powerful car on here is Wyns? However I believe its not actually any faster down the strip than Johnymd's was. I know you see a lot of higher hp S30's in america, but if you watch them, none of them can put down the power in the first 3 gears and they mostly look pretty unusable on the road and you hear a lot of them complaining about them. Y0u won't hear me complain about mine as its completely usable and drives perfectly on the road. Most of the time I actually only run it on low boost which is around 400hp and its still super fun at that power, it can handle high boost well, its just that its already so fast I don't often feel the need for the high boost setting.

    It helps that I have 490lbft of torque and make full boost by 3800rpm. I love the great midrange power and I have 375hp and 475ftlb at just 4000rpm which makes motorway driving a lot of fun, just squeeze the throttle and it shoots off, effortless passing.
     
  17. franky

    franky
    Z Club Member

    Spend the money wisely on a 2.4ltr 9000rpm screamer and enjoy the added coolness that’ll bring to your life.
     
    Woody928, datsfun and atomman like this.
  18. Rob Gaskin

    Rob Gaskin Treasurer Staff Member Moderator

    I had a lot of cheap fun with a 240Z that was about the same power/weight as this Mazda.

     
  19. Rushingphil

    Rushingphil
    Z Club Member

    Why three though :conf2:
    Surely one each side would suffice? :D
     
  20. TheHulkGB

    TheHulkGB
    Z Club Member

    Thanks to everybody's advice I’ve revised to target power goal to 450-550hp. I’ve had cars which are more powerful then this so wasn’t sure if this level would be suitable. The points raised by members regarding drivability are important as there is no point throwing money into a RB to get to 800hp and not be able to put it down. It’s a shame as I was looking forward to seeing what that would feel like.
     

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