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BBC vs LS#/X Need Advice Please

cliles

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It has been quite a while since I have updated my CK5 build. I renovated a foreclosure which really got in the way of my 454-496 stroker engine build, but now I am back at trying to upgrade my 90 K5.

After doing a lot of engine simulating and cost estimating, I decide it made more sense (both from a time and $ standpoint) for me to just buy the 502 ram jet crate engine then having the 454 that I pulled stroked & bored to a 496, piecing together the EFI setup or buying a "plug & play" kit from Holley, Fast, etc. I know those with tuning skills will probably disagree, but I do not currently have that expertise and I am trying to get the project done by mid-summer.

Just when I was about to add the 502 RJ to my cart, and piece together the accessories I read that for the same-ish $ amount you could build or buy a LS3 turnkey crate which would give you similar to more power, be lighter, and more fuel efficient (everybody agreed LS7 is better option but to pricey for my budget, and LS3 seem to stand-out as the best of the other LS options).

However, after trying to research this for several hours, I only came up with peoples opinions without much back up. Most of the threads were LS-something vs BBC, and the BBC option was always carb'd. That to me seems like a clear apples and oranges comparison. Especially when talking about drive-ability and fuel economy.

So my questions are...

1. I feel like I would be very happy with the RJ's hp/tq curves, is it reasonable that I could get an LS3 turnkey that has a similar tq/hp distribution (that high & flat torque that the 502 has and a BBC is known for).

2. Would there really be any savings as for as MPG's? I know that gas mileage is not something that most of us are concerned about, but it seems foolish to disregard since I want to do a lot of road driving and we are talking about spending similar dollars, so why not get something that is more efficient.

3. Outside of the engines contribution to MPG's, what about the weight difference. I could never find the approximate weight of either engines, just that the LS3 was aluminum, and therefore should be lighter.

4. Reliability - a lot of people commented that the LS3 was more reliable (once again this was often compared to a carb'd BBC of any kind). Thoughts? People also commented that GM builds crap engines and the RJ is just that. All of those people were building GM vehicles, so I did note the hypocrisy, but is there anything to it? Would a RJ or LS3 built by a third party shop be inherently better than a GM built option?

5. Compatibility - Would the LS3 be more or less compatible with my 4L60E setup that I am currently running?

Anything else I should know/do?

Thanks,

Chris Liles
 
generally with the BBC I believe you will have more room to increase the performance later
also you can stroke and build your 454 to deliver more power/torque than the RJ502

FYI, Holley Avenger MPFI system can self tune it self and is very easy to manage
check the below link for more details
http://www.chevelles.com/forums/showthread.php?t=326671


if it was me, I will analyze the below two options and then decide

Option 1:
- buying a turn key LSx engine - $xxxx
- building a new exhaust system, headers, etc .. - $xxx

Option 2:
- stroking and building the BBC you have - $xxxx
- Holley Avenger MPFI system - $xxxx
- use the current exhaust , headers ... etc - free
- use the current BBC accessories - free
- OR, buy Kwik performance Big Block Chevy Serpentine Belt Conversion Kit and source SBC serpentine kit from junkyard - $139+
http://www.kwikperf.com/bbc_serp_kit.html

also you can save more money if you can find used EFI hardware and just buy Holley avenger MPFI ECU, harness and injectors

for example, I've just bought Holley BBC MPFI intake manifold, fuel rails, FP regulator, 1000 CFM throttle body, sensors (TPS, IAC, CTS and IAC) with an old obsolete Haltech ECU and wiring harness for $400 :thumb:


if MPG is a big factor for you, this guy achieved 17.5 MPG on his 502 BBC with Holley MPFI avenger and more cab be achieved with more tuning
http://www.chevelles.com/forums/showthread.php?p=2937063&highlight=mpg#post2937063
 
Thanks so much for the advice. MPG is not a huge priority and I know it will never be good; however I would hate to pay $10k for a guzzler when I could have gotten 3 mpgs better from and equally powered ls3.

Question though, what do y'all have against the ram jet?

Thoughts about using the ramjet intake and fuel rails on a 496 or is Holley, fast, etc the way to go?
 
I should note, that while I have a Gen VI 454, long block, I do not have all the accessory assembly & the block has never been installed. So I will have to remove my 350 TBI and basically start over as far as fuel pump, radiator, accessories, exhaust, etc.

The big block definitely gives you more room for improvement, however not to be a pussy, but if you start building for +600 numbers you are going to be breaking everything behind your engine, all the time. I am a little nervous going as high as I am, but I have a 400 hp Dodge Ram and that kind of performance will not cut it for my Betty.
 
Question though, what do y'all have against the ram jet?
because it is overpriced and underpowered
guys are making 500+ hp/ 550+tq on over-bored 454 with ported peanut heads (search on chevelles.com for threads started by vortecpro)

here are some examples
http://www.chevelles.com/forums/showthread.php?t=321019&highlight=236
http://www.chevelles.com/forums/showthread.php?t=342085&highlight=236
http://www.chevelles.com/forums/showthread.php?t=315172&highlight=236

Thoughts about using the ramjet intake and fuel rails on a 496 or is Holley, fast, etc the way to go?
I think it is more expensive than other alternatives such as single plane efi intakes
you can also use a mercruiser BBC MPFI intake if you wish

with a little more than $10000 you can build your BBC,add an EFI system and also a 4l80e to handle the torque of the BBC
 
I really appreciate your prompt response and help. I have simulated several engines in desktopdyno and match to a couple of powerblock and hot rod mag builds. Would you mind if I sent you a parts list sometime, and perhaps you could advise me where to trim the costs?

As far as cost savings from junkyard shopping, I am traditionally for it but I am on a time crunch bc of a baby on the way. So if I can not find the part quickly at the scrapper then I need to budget for new. That being said, my time will be more limited upon completion and I need to have as few of reliability issues as possible.
 
I'm building a mild 454 right now, hoping to have it by the end of the week. Motor is nothing special. 1986, 2 bolt, cast crank, 3/8 ARP rod bolts. .030" over, KB pistons, roughly 10:1, high volume oil pump, 781 heads, gasket matched intake ports, stock as far as I know other than that. Cam is a Sealed Power, can't remember all the specs, but little over .500" lift, supposed to have a "fair" idle. Range is 1800-5800 IIRC. Professional Products dual plane intake, 600-ish carb and good flowing exhaust.

Guy who is putting the motor together has been doing this for years, so he is not a noob when it comes to engines, especially big blocks. Past experiences says the motor will be around 375-400 horse, and over 450 ft/lb of torque. After buying the engine for $600, heads for $225, and all parts, machine work, balance and assembly labor, I'll have little over $3k into the motor. This is a completely rebuilt motor.

If you have TBI now, you don't have to change the fuel pump, they are the same SB to BB. LS will require for pressure. The computer is basically the same, just change out the PROM, both should be available on Evilbay. Wiring is essentially the same too, couple connectors may be different. Accessories is easy, I'm doing this to my motor. Get a complete serpentine setup off an 88-up truck, S-10 or even a Firechicken or Camaro, reverse rotation waterpump, and brackets off evilbay.

I'm not a fan of the LS motors. Buddy's have some, 5.3s and 6.0s, none have the torque of a big block.
 
I have the LS3 in my new camaro and it's a power house. They are very easy to get lots of power out of. But I will say that for a truck the power band might be a little higher in the RPM range than you'd get with a BBC but you get more RPMs out of it so its just a matter of keeping the rpm higher than you're used to.

I think that the ramjet is a bit dated, go for an LSX. You will get the same power and definately better fuel economy.
 
LSX Economy

I think that the ramjet is a bit dated, go for an LSX. You will get the same power and definately better fuel economy.

Keep in mind, I have read a lot about engines, but never built one, so you may have to humor me. I know the LSX is designed to come in various bores, are you suggesting that a smaller bore on the LSX will lead to better MPG's? Something else inherent with the engine?

Most of the turnkey LSX's I have found are going to be an easy +$3k more than the Ram Jet, they all make more HP, but nothing I have found has torque curves like the Ram Jet (see attachments). $3-$4k incremental leads to a long payout in MPG increases.

Not to kick a dead horse, but I am not seeing what is wrong with the Ram Jet. I did look into Blueprint_Engines' PSLS4272CTF, that TRusty suggested, and it does sound very badass. However, Blueprint Engines does not have it listed on their website & jegs does not have a dyno sheet. I have put a request in through their site to get one though.

Thanks

Chris Liles

502 RJ Dyno Sheet Page 1.jpg

502 RJ Dyno Sheet Page 2.jpg
 
Keep in mind, I have read a lot about engines, but never built one, so you may have to humor me. I know the LSX is designed to come in various bores, are you suggesting that a smaller bore on the LSX will lead to better MPG's? Something else inherent with the engine?

Most of the turnkey LSX's I have found are going to be an easy +$3k more than the Ram Jet, they all make more HP, but nothing I have found has torque curves like the Ram Jet (see attachments). $3-$4k incremental leads to a long payout in MPG increases.

Not to kick a dead horse, but I am not seeing what is wrong with the Ram Jet. I did look into Blueprint_Engines' PSLS4272CTF, that TRusty suggested, and it does sound very badass. However, Blueprint Engines does not have it listed on their website & jegs does not have a dyno sheet. I have put a request in through their site to get one though.

Thanks

Chris Liles

When I said LSX I meant the series of engine and not the "LSX" GM crate engine. The ramjet will work for you don't get me wrong but there are so many more cool stuff you can do with a LS-series engine. The LS7 is over priced, but the LS3 is right on the money and would be worth it. Since you are replacing a small block so you need all new accessories, motor mounts, headers, exhaust, and fuel system reguardless so I feel the swap parts are pretty much a wash. It all depends on what you want more a big block or a LS3 :deal:
 
When I said LSX I meant the series of engine and not the "LSX" GM crate engine.

See I told you that you were going to have to humor me. As far as BBC vs LS#, its not a pride/style issue for me. I just want the best bang for the buck that can ideally replicate torque curves like the RJ.

I have request in with several builders for dynosheets (instead of just peak #s) for their LS3, L92, and LQ9 setups, here are a few

http://www.southernperformancesystems.com/BaseEngines/ls3-546-b-rod.html


If nobody can get close to the torque curve of the RJ then I am going with it. I know a mechanic that thinks he can get it for a decent amount below list price and cut the shipping. So worse case scenario, if I made the wrong choice, I will still come out cheaper. Also if I get the RJ, I think I will probably install roller rockers and have the PCM flash'd prior to installation. Should net me some hp's, mpgs (supposedly RJs run rich), and extra miles for around $450.
 
evaluate this combo

- buy a built 475 BBC from mark jones (vortecpro) - $5000 (I couldn't find his listing in ebay but you can contact him and confirm the pricing and verify if he can built your core and save some money
don't forget that you won't buy the carb or the distributor, so it should be cheaper)

- Holley MPFI Kit - $2910.99 - 3099
http://www.holley.com/550-836.asp
http://www.nextag.com/HOLLEY-550-836-Avenger-1264183432/prices-html
http://www.amazon.com/Holley-550-836-Avenger-Multi-Point-Injection/dp/B004BA0MN0

- Kwik performance Big Block Chevy Serpentine Belt Conversion Kit - $139
http://www.kwikperf.com/bbc_serp_kit.html

- existing SBC accessories and brackets from your 90 K5 - Free

- existing HEI distributor and coil from your 90 K5 - Free

- Headers - $129.95
http://www.summitracing.com/parts/SUM-G9011/

-------------------------------------------------------------------------------------
Total = $8178.99


I will not consider the full exhaust, radiator .... etc because you need to do them either for the BBC or the LSx
 
Won't be able to use your existing pulley brackets, those Kwik fit are designed for the aluminum ones off the new body style 88-up or -body cars. Both are easy to get tho.
 
Dyno Sheets

I received several dyno sheets from one of the guys at Southern Performance Systems, but for some reason this forum has a very low max size on pdfs? Almost 2 MB for pictures and only 19.5 kb for pdf. I will see what I can do to enter them into excel so they can be plotted against the Ram Jet.

The #'s were pretty impressive, but outside of the supercharged models, none of them have the low end torque of the Ram Jet.

I hate to keep going in circles on this, but it would I be happier saving $ with a carb'd engine. $3-4k makes up for a decent amount of ****ty gas mileage. Are they as big of a headache for daily/driving reliability as people say?

Thanks

Chris
 
Fuel injection is the way to go. I used to be a diehard Carb guy but after I couldn't get a Carb to tune right for a year I went with the FAST EZ EFI. That system is badass and only costs about $2k. Its self learning and tuning and pretty easy to install. Now having efi I won't be going back to carbs ever. No choke, no waiting to warm up, no need to tune ever, runs great in every condition, better mileage, and better reliability.

Btw why be stuck with Holley mpfi when the fast system is newer, cheaper, and more user friendly?
 
Won't be able to use your existing pulley brackets, those Kwik fit are designed for the aluminum ones off the new body style 88-up or -body cars. Both are easy to get tho.

I believe he have a 1990 K5 so it should already have the aluminum serpentine brackets
 
Btw why be stuck with Holley mpfi when the fast system is newer, cheaper, and more user friendly?

I mentioned holley as an example only, he can go with any other brand in the market

BTW FAST EZ EFI is a fuel only setup it doesn't control timing AFAIK
please correct me if I am wrong?
 
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