iansmusical

Hi Guys,
Before I start I've spent a lot of time reading many postings and PMing people on engine swaps to gauge opinion and what's best but still aren't quite sure

I currently have a 91 3.1 V6 Firebird and already know that the cheapest and easiest swap is to a 3.4 V6 and that gives me 20bhp more but I should point out that I'm not looking to do any mods, just swap stock for stock etc. That leaves me with swapping to the LB9, L98, LT1 or LS1.

From research going to the V8 will automatically require me to replace the suspension, exhaust, transmission, ECM, harness and engine mounts/K member? The LB9 as I understand is good but a crippled L98 and given the L98 has more power/torque and the same fuel economy, that would be the obvious choice However, the LT1/LS1 is newer technology, has even more power/torque and perhaps better economy wise (not sure how much though?) but I think a lot more work is required compared to dropping in the L98, which was always meant for these cars. I probably also should say that I can't fabricated parts and don't have an endless budget!

Now moving to the issues, with the price of fuel here I still need economy, which the LT1/LS1 will provide but would cost more to get in the first place. I think on balance the L98 and 3.1 probably return the same economy, 1-2 mile difference!? The major issue with being in the UK is getting the engine and transmission For you guys getting a good one seems really easy and cheap! I'm wondering if one of you would take on the task of fixing me up with one but I'm not sure how much shipping would be to the UK as yet!?!?

Thanks, appreciated

Ian

Z28ricer

iTrader: (2)

Ian, first i'm going to start out by addressing your list of things to change when going V8, as there is a LOT of misinformation out there on the subject.

Heres your list of what needs to be changed: suspension, exhaust, transmission, ECM, harness and engine mounts/K member?

Suspension, they are all the same except for the 82 ? K member, yes some people have done swaps on worn out 1985 cars and needed to put better springs in, they're worn out, i've done the LT1 swap to a few 91-92's and they could still use lowering springs. Another thing to consider here, is that either way your springs are old and a good set of shocks and struts along with springs, would be just about a necessity to anyone with any sorts of intelligence building a thirdgen.

Exhaust: Yes your manifolds and Y pipe wont work, thirdgen headers would be the ideal piece for the swap, as far as the catback, again kinda the same boat as the suspension, you can easily reuse your catback if you NEED to, it wont provide optimal flow for any reasonable power, but your catback is the same one used on the 5.0 TBI and non G92 5.0 TPI cars. And just like the springs, its small, restrictive, and probably might even fall apart soon, its going to be needing replacement no matter which engine you choose.

Transmission, dont know if your car is auto or T5, but technically if you were doing a mild swap and not going to beat the snot out of it, the V6's T5 can be used on a V8, its not ideal, but it will work till you can get a better trans. If you are auto, then this doesnt apply, no removable bellhousing on it, toss it in the trash.

ECM/Harness: Actually the ecm is the same as the 90-92 TPI cars, the prom "chip" would need to be changed, and a small amount of work done to the wiring harness, but you could use it with a TPI V8. LT1 / LS1 yes you'll need to do something different, though the gains for just changing the harness and a few other little things are well well well worth it.

Engine mounts / Kmember, k mems are the same, engine mounts, standard thirdgen V8 mounts are used for of course the tpi swaps, and are also used for the LT1 swap, the LS1 is where things get a little bit more involved, but not too bad, the main trouble is a/c comp clearance.

Some of the things you havent provided that might help with suggestions :

1. Do you have any emissions or other swap laws that you'll need to tiptoe around ? (every swap here usually ends up different due to this, we've got different things people have to consider for the states testing here)

2. A/C , is it going to be retained or has it already been tossed out the window.

3. What is your actual budget ?

4. Is your car auto or manual, and do you wish to change it or stay the same ?

5. What is the parts availability for each engine if at all for any, like over there ?


My suggestion is usually LT1, the balance of cost / power vs the other choices makes sense to me, mainly because from what i've seen its going to cost less up to 440 rwhp, and above that is where the LS1 starts to see a benefit, being that i dont really need 450+ rwhp NA in a thirdgen for daily driving, at current prices its still out of the question.

iansmusical

Thanks very much for your comments and to answer your questions.

1. We have an MOT test every year, which checks for emissions etc and I'd have thought they'd have to be within the tolerences for the car in US spec form. For example, I don't think I'd be able to remove the cat and not worry about emissions!

2. The A/C would need regasing for a start but it depends how easy it is to retain or not really, as I'm personally only using the car in the summer, when I would perhaps need it.

3. My budget is perhaps 1000 pounds ($2000) not massive and perhaps why I was leaning towards the L98.

4. It's an auto (with overdrive) and 3.22 rear axle, it's stock I believe but obviously the auto would be trash now!

5. Suspension, exhaust is available here but if I can buy the engines they would be really expensive... someone said a chevy crate would be 1500 pounds!!! Maybe 1000 pounds for a V8 (not sure which model though!)

The current suspension is as you say 17 years old and it's FE1 (soft!). The exhaust has been changed (not by me) so that the pipe splits into two mufflers instead of the one in two pipes out type.

For me the LT1 swap sounds expensive compared to L98 and personally I'm not looking for 400bhp+, given I have 140bhp now. 7 secs to 60 in an L98 would do me I'd perhaps consider a 4th gen in a few years to get down to 5 secs! The only thing that puts the LT1 top is if it gives much better economy.

Thanks, appreciated.

Ian

Z28ricer

iTrader: (2)

As far as economy, the 350 TPI 1991 Z28 is rated at 16 City 24 Highway
1995 Z28, auto 17/24, and manual 17/26, and this is in a car thats typically about 500 lbs heavier than a thirdgen, the one swap that i've been able to actually calc, was getting around 21-22 mpg city, and 30 highway isnt too hard.

Your budget seems to be the hardest part, realistically the pricing isnt too far apart for L98 vs LT1, especially with the LT1 having more power, more economy, easier to work on, lighter, better drivability, etc.

Your budget it would seem would make even getting everything from here and shipped over there, and when you are going to spend a chunk of money paying to have parts shipped over it really doesnt make sense to have the inferior stuff sent when much better is available for only a small price difference.

With only $2000 available, and taking shipping into consideration, if i were you i'd either start buying pieces for the LT1 swap knowing i'll need more to complete it, or just keep your money in the bank until you have the money.

sid rs91

hey Ian I was just wondering with your current budget ,have you looked in to a swap from other cars that you can get there?

I left england along time ago but a mate of mine would drop rover engines (cant remember which one's) in to his cars. he had one in his capri and cortina.
unless you want to keep it chevy but its another option,as for fab work I'm sure a local machine shop could help you out.

Z28ricer

iTrader: (2)

I found an autotrader page for the UK to try and get an idea of what else you might be able to source an engine from, thinking that maybe the holdens might be plentiful enough there for you to get an LS1 from, but that doesnt seem to be the case.

I did see that supras werent very expensive. A 1 or 2jz swap wouldnt be a bad thing to consider if you can round up some fab skills.

iansmusical

Hey sometimes I think about leaving the UK myself and maybe I will one day

I'd ruled out engines from other manufactuers because I've heard too many people on here talk about fabricating costs, I can't weld etc and really wanted to just get the parts and put it together (without being simplistic) and hence why the L98 seems the best bet because it belongs in there anyway.

I found a 350/290bhp small block crate engine here and that's at least 1600 pounds... have you forgot about rip off Britain My budget is quite low but when you consider I paid 1400 pounds for the whole car and it's in great condition, I really can't spend 2000 pounds on it etc!

Thanks,

Ian

iansmusical

The thing with the UK is there are a good few people that have US cars of all brands, we have POC, ACCINT clubs that are quite big but the majority of people here have European, Japanese cars etc. Most cars are 4 cylinder, some smaller ones are 3 cylinder, my other car is a 3 cylinder diesel Some of the more expensive bigger cars are V6 and while we love V8s they're as rare here as a car smaller than a Rabbit/Golf there!

The Holdens are big in Australia but none here, well I've never seen one! The Supra idea grabs me but I really don't have fabrication skills... I'm more electronics!

Thanks,

Ian