Setting my ride height before fuel cell install s13

[RedSiBaron]

Hey all. In order to comply with scca rules, my fuel cell needs to be a minimum distance from the ground, so before choosing my fuel cell I want to get my ride height as close to optimal before installing the fuel cell.

What is considered the optimal ride height for the suspension geometry on the s13. granted I understand there is a lot of factors to consider but I am looking for some direction on where to start. I've been reading on the forums and a lot of people seem to say that you can get the s chassis as low as you want and a lot of the geometry can be compensated for or am I misunderstanding what I have read?

that said, could it be that when placing a fuel cell of 12-15 gallons in the oem location, most of them dimensionally dont come anywhere near the ground and thats why I cannot find anyone talking about it here on the forum? My car is currently not at my home so i cannot crawl under it right now to explore this idea.

thanks in advance.

[Def]

What can you do to the suspension? If you can relocate suspension links/pivots in the front and pull the rear subframe up to the body you can run these cars reasonably low (maybe 3" to the framerails give or take about 3/8").

What's the requirement for ground clearance? Putting the cell in the stock location on an S13 probably won't have an issue with ground clearance. You can cut the trunk behind where the subframe mounts to get some more headroom as well.

[Matt93SE]

What class are you building such that you need a fuel cell? and why so large? my car burns 6 gallons in a 45 min race on a long track. I see no need for anything larger than maybe a 10 gal cell unless you're running a lot more power and burning more fuel.

[RedSiBaron]

What can you do to the suspension? If you can relocate suspension links/pivots in the front and pull the rear subframe up to the body you can run these cars reasonably low (maybe 3" to the framerails give or take about 3/8").

What's the requirement for ground clearance? Putting the cell in the stock location on an S13 probably won't have an issue with ground clearance. You can cut the trunk behind where the subframe mounts to get some more headroom as well.

I am not 100% on what i can do to the suspension, but I will double check if i can move pivot points or moving the subframe up. I am fairly certain I can at least get away with moving my subframe up.

I just sifted through the new 2014 GCR and it doesn't look complete, so I will have to find an older PDF on my home computer and look in the safety section, but going off of my memory scca wants the bottom of the fuel cell atleast 6" off the ground, and obviously i want it as low as possible within the rules to keep my CG as low as possible.

Since SCCA has certain rules that pertain to all classes, like cages, fuel cells, restraints (pretty much safety) if it required within the class, it is in a safety section, not the class specific section, so in the 2014 gcr it is currently missing

What class are you building such that you need a fuel cell? and why so large? my car burns 6 gallons in a 45 min race on a long track. I see no need for anything larger than maybe a 10 gal cell unless you're running a lot more power and burning more fuel.

I am building most of the car to comply with gt3 rules (mostly just using that as my safety guide) but I cant afford to build a tubeframe car currently, so I wouldnt be competitive. I'll mostly just run time trials and then global time attack (which has pretty vague and lax rules). I can't afford to run wheel to wheel currently. Ill probably also run some nasa lapping

Basically, scca dictates some of the most stringent safety standards, and if you comply to that, they will comply everywhere.

I was leaning more towards a 10gal, but I am hoping to do the silverstate classic some day and i know that will require a bit of fuel down the road. Also it currently makes about 340, but who knows if down the road I'll want 500ish. its an sr20 by the way. I think my logic on the 12-15gal is so i dont have to change it out later as power goes up since that will be a bit of cost to change, not to mention the extra fabrication of building a new frame/cage/box for the new cell.

[Matt93SE]

There is currently no SCCA Club Racing class that allows the SR20DET, especially at those power levels. I have considered an attempt to get it classed for STU, which is more along the lines of a 'tuner car class' than GT3.

however, if you're not intent on going club racing and just using it as a safety guide, then you're good.

The 2014 GCR at 884 pages is VERY complete. if yours isn't that long, then try downloading another copy- maybe your downloaded file was corrupt or something.

The way the rulebook is written, much of the 'general prep stuff' like fuel cells and cage requirements are in a different section than the car-specific or class-specific stuff in the GTCS.

For the Jan 2014 GCR, all fuel cell related info is in sec 9.3.27 on page 98. it covers mounting and type information. There is nothing mentioned about min ground clearance, BUT that is mentioned in the individual class rules for each class. i.e. Min ground clearance for STU is 3.5" IIRC, which covers everything on the car- not just the fuel cell.

If you have specific questions on the SCCA rules, I'll be happy to try and help-- been through that book a bazillion times building my STU car, so I have a good idea of how it's laid out and such.

[icantdrift]

I have a 12gal Fuel Safe in my S13, with the top of the container slightly below the flat part of the original trunk floor. My car isn't slammed by any means, but it's low and while I haven't measured ground clearance for the cell I know it's plenty more than 6".

[RedSiBaron]

Ya i figured the sr20de under the gt3 class allowed vehicles and engines was the one out of the sentra. I feel bad for anyone thats prepped a car for a class and thought their det would pass.

Ya I am already building a GTL (very long time coming) 86 crx, don't need 2 GT cars unless my father wants to kick my ass. I just generally follow GT class rules for safety. I already looked into global time attack and their rules are extremely vague and read more as suggestions when compared to sccas. That said nasa allows the DET so I am sure I will have no problem with time trials or lapping. Dont care if the car starts out non competitive, just getting all my safety done the first go round and the performance will be the area I spend time developing.

I was looking for that section since it kept getting referenced, so i guess you are right that my file must be bad. I appreciate the help a lot.

Icantdrift, That makes me feel better as I don't imagine the car ending up much lower than that, and i was planning on going with the internal surge tank/pump fuel safe.

[RedSiBaron]

Real quick mention, I just re downloaded the GCR and on page 98 it does say the fuel cell needs to be a minimum of 6" from the ground or within the bodywork in oem floor pan.

what does it mean within the oem floor pan? does that mean the bottom above the floor? does that mean passenger compartment floor or just floor pan in general meaning front firewall back to the rear?

[Matt93SE]

what they're meaning is that it needs to be 'inside the body'
Some of the fuel cells out there are designed to fit inside the spare tire well (I think there's a few models for BMW 3-series).

In these instances, sometimes the trunk floor is lower than 6" off the ground, so they stuck that line in there.

For an S13, I wouldn't think you'd have a problem mounting it flush with the floor just like icantdrift's.