How much?
Advanced
Joined: Jun 2003
Posts: 53
Likes: 0
From: Mission Viejo CA
It depends on who does it and what part of the country you are in.
I recently asked this same question on my '91 L98 and did a bunch of research. I ultimately found someone in my area of SoCal who has done many C4's in the past and from listening to him talk, I can tell he has. The verdict: it would be more cost effective to replace your motor with a crate motor like a ZZ350 or ZZ383. It's the labor that eventually raises the price.
We did a detailed estimate to do my 1991 and convert it to a ZZ383 plus (in addition to just the motor), the complete TPIS bolt on treatment (long tube headers, big mouth lower plenum, big tube runners, port matched upper plenum, larger throttle body, new ECM, etc.). Total came out to $10k including labor. Here is the breakdown:
ZZ383 crate motor: $5k
TPIS bolt ons: $3k
Labor: $2k
The ZZ350 is approx $1k less than the ZZ383.
The gain will be approximately 75-100 bhp for the ZZ350 (up to 350 bhp) and about 150 bhp for the ZZ383 (up to 450 bhp). It all depends on the bolt ons and how well they work together and how accurate the ECM can be tuned. TPIS offers off the shelf preprogrammed ECM's for up to 383 cu inch engines that are highly modified. The thing is, tuning the C4 L98 ECM is very difficult and requires a real specialist to do it. Otherwise, it can easily be f....ked up. That's why it's better to get a pre-programmed one. It is unlike today's modern PCM's, which can be tuned much easier by almost anyone.
In my personal opinion and experience, the only way you can really save money when doing engine swaps/rebuilds is if you do the labor yourself. Doing engine swaps is not that difficult IF you have the right tools, time, and can read a Service Manual. If you can change the spark plugs and do the tune up on your C4, you should be able to do an engine swap on it as long as the engine is a bolt on deal (like in the case of the ZZ350/383) If you do the rebuild yourself, you will need more tools, time, and patience, and a proper book/coach to help you along. But again, building SBC is not rocket science as long as you stick with the basics and not go into anything bigger than a 383. Like anything, having someone who has done it before helps immensely!
Hope this helps.
I recently asked this same question on my '91 L98 and did a bunch of research. I ultimately found someone in my area of SoCal who has done many C4's in the past and from listening to him talk, I can tell he has. The verdict: it would be more cost effective to replace your motor with a crate motor like a ZZ350 or ZZ383. It's the labor that eventually raises the price.
We did a detailed estimate to do my 1991 and convert it to a ZZ383 plus (in addition to just the motor), the complete TPIS bolt on treatment (long tube headers, big mouth lower plenum, big tube runners, port matched upper plenum, larger throttle body, new ECM, etc.). Total came out to $10k including labor. Here is the breakdown:
ZZ383 crate motor: $5k
TPIS bolt ons: $3k
Labor: $2k
The ZZ350 is approx $1k less than the ZZ383.
The gain will be approximately 75-100 bhp for the ZZ350 (up to 350 bhp) and about 150 bhp for the ZZ383 (up to 450 bhp). It all depends on the bolt ons and how well they work together and how accurate the ECM can be tuned. TPIS offers off the shelf preprogrammed ECM's for up to 383 cu inch engines that are highly modified. The thing is, tuning the C4 L98 ECM is very difficult and requires a real specialist to do it. Otherwise, it can easily be f....ked up. That's why it's better to get a pre-programmed one. It is unlike today's modern PCM's, which can be tuned much easier by almost anyone.
In my personal opinion and experience, the only way you can really save money when doing engine swaps/rebuilds is if you do the labor yourself. Doing engine swaps is not that difficult IF you have the right tools, time, and can read a Service Manual. If you can change the spark plugs and do the tune up on your C4, you should be able to do an engine swap on it as long as the engine is a bolt on deal (like in the case of the ZZ350/383) If you do the rebuild yourself, you will need more tools, time, and patience, and a proper book/coach to help you along. But again, building SBC is not rocket science as long as you stick with the basics and not go into anything bigger than a 383. Like anything, having someone who has done it before helps immensely!
Hope this helps.
Advanced
Joined: Jun 2003
Posts: 53
Likes: 0
From: Mission Viejo CA
I wanted to add that the price of ZZ350/383 motors are higher than a standard SBC because they are most definitely high performance motors.
You can get less costly crate SBC that can put out up to 275-300 bhp out of the box. Just NOT if you fit it with your stock TPI components. Then, you will be back to the standard 250 bhp range. Also, these SBC crate motors will have iron cylinder heads that are heavier. I think most of them will have the fast burn iron heads but I may be wrong.
The ZZ motors are GM built and come with hefty warranties, which I think goes to 2-years and 24 months.
The biggest issue with rebuilding motors is who can you really trust. Many places, companies, individuals will claim experience, quality, power, reliability, and low price. But only a few can deliver. And those who can usually will charge you extra.
You can get less costly crate SBC that can put out up to 275-300 bhp out of the box. Just NOT if you fit it with your stock TPI components. Then, you will be back to the standard 250 bhp range. Also, these SBC crate motors will have iron cylinder heads that are heavier. I think most of them will have the fast burn iron heads but I may be wrong.
The ZZ motors are GM built and come with hefty warranties, which I think goes to 2-years and 24 months.
The biggest issue with rebuilding motors is who can you really trust. Many places, companies, individuals will claim experience, quality, power, reliability, and low price. But only a few can deliver. And those who can usually will charge you extra.
