Engineering a TJ

[jwrangler]

I have spent the last 6 months investigating getting some more grunt out of my 2004 TJ 5 Speed.

I have looked at the following.

Superchargers and turbo chargers - cheap but the electronics and tune cost as much as the hardware.

4.7/9 litre stroker - cheap but not sure of the bang for buck return and of course there is that bloody 04 TJ ECU to deal with along with fuel comsumption towing a camper trailer.

Looked into an LS1 then all the other stuff that needs doing, clutch, linkages, mounts, driveshafts etc...

Should i go auto 4l60/e - T400 or retain the jeep 5 speed - keep the 5 speed jeep manual to keep the engine braking. I actually use my TJ as a 4wd not just parking it on the grass once a week.

I decided and was talked into the 5.7 LS1 by a few workshops that i know from the dark ages when i raced.

I am busy with collecting the parts from local and US suppliers.

Today i spent a few hours on the phone trying to establish what the cost/requirements would be to have the car engineered because i want to do it properly so i can enjoy my toy without watching over my shoulder.

I was quoted today the following prices and they vary hugely!!

Engineering of the engine and associated items - $495 - $1,800

Engineering or the rear brake conversion to disc - $800 - $4,000 yep $4000 dollars to say that an OEM 04 TJ Rubicon rear disc upgrade is safe! Some BS about hiring Eastern Creek raceway to do a lane change test..

Engineering lift and tyres.. don't even go there..
33 inch tyres - Not passable
2.5 inch lift - not passable
1 inch body lift - if suspension lift is greater than 1" not passable.

So there you go, i can stuff a 5.7 litre ball tearing v8 into my TJ without issue.
But it may cost me $4000 for an engineer to say what Jeep said back in 2003 in regards to putting rear discs on my TJ.

33" tyres, 2.5 inch suspension lift & 1 inch body lift make my TJ into a death trap unable to be registered.

Seriously, is this true?
I am speechless.

JWrangler

[SeaComms]

I wouldn't have thought you would need to have the rear disc upgrade engineered since it was a factory option on that model?

As for the rest, yep, same up here in QLD. Bloody ridiculous.

[jammy jeep]

It cost me about $800 to have my rear disc conversion engineered. $4k is crazy

[chris0375]

Basically comes down to how much an engineer likes your plans. They can sign off on a lot of stuff but they are then responsible. If you want bigger tyres etc new diffs would possibly be required.

I get the impression a lot of engineers steer clear of lifts and tyres. Too much attention and questions if you were to crash and someone was too get hurt.

Many are conservative and rightly so, it's their career at stake.

[jwrangler]

After a few more enquiries today i found out that the engineers that i rang really do not want to do the job mainly because it is not their area of expertise so they over priced the job.

I spoke today with another engineer who does this all the time and his prices are fair.

I fully understand that the engineer is liable for his approval. I have no issue with that and i do not want to build an inferior car. I always buy the best and don't cut corners.

If the engineer thinks it is unsafe then it is his responsibility to not approve the car.

[low ranger]

be careful here mate, The RTA can choose to ignore certification making your investment worthless. They only have to say that they don't agree with the certification & your back to square 1

[MidnightRiders]

I also looked into this last year. Spoke to an engineer in blacktown. He told me that with four inch suspension lift plus 33" tires will be difficult because of the moose (maneuverability) test. I've heard of it being done at 70Kph, he does it at 100 Kph. He was willing to do it for $1800 plus track rental which could be split between others if i got a bunch of people to go. But no guarantee of a certificate.

I just made sure i listed mod's with insurance company and they agreed to cover me. I use best judgement when driving and buffer to reduce chances for an accident.