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What are the physical limitations of the N/A 3.8? What kind of rpm can you spin them to before other factors become a problem?

Since the one I'm working on may someday have SC parts currently it's getting ARP studs, felpro permatorque head gaskets, and an SC oil pump. If I decide that N/A is enough for me and want to start spinning it higher what issues am I going to run into. Basically fast can I spin the N/A 3.8 rods, valve springs, and crank before they go to hell in a hand basket?
 

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What are the physical limitations of the N/A 3.8? What kind of rpm can you spin them to before other factors become a problem?

Since the one I'm working on may someday have SC parts currently it's getting ARP studs, felpro permatorque head gaskets, and an SC oil pump. If I decide that N/A is enough for me and want to start spinning it higher what issues am I going to run into. Basically fast can I spin the N/A 3.8 rods, valve springs, and crank before they go to hell in a hand basket?
I don't care for the 3.8L engines one bit and I wouldn't trust them to rev high at all. Maybe 6000 tops and not on a regular basis.
 

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I don't think its even that high.. I have an article or two actually on the 3.8 L.. let me see if I can find it..


aha! here's one... http://www.mre-books.com/sa106/hipomustang6.html
haven't read it in a long while but from just skimming through safe rpm is about 5,500 :zdunno:

I think there's another article here somewhere..

Can't find the other article but after a quick search on the TN mustang forums I'm on seems like the general consensus is 5,500 rpm due to the drop off in power after 5200 rpm but mainly because the valve springs are junk. HTH
 

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I'd trust an SC shortblock at 5500+ RPM over a 5.0 shortblock at 5500+ RPM.
Why is that? I have yet to have a 5.0 shortblock fail from rpms. Usually the block itself will split from the power before any of the stock rotating assembly fails. I've revved stock 5.0 bottom ends to 7K without issue. Now the stock 5.0 valve springs and top end are a different story, and I have floated the valves in stock E7 heads at under 6K rpms, but with upgraded heads, cam, and intake, I see no reason why a stock 5.0 bottom end can't handle at least 6500rpm regularly.
 

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Well first I admittedly misread Chris's post, thinking "SC parts" implied full SC swap(top and bottom end) and what the RPM limits of that would be. So my statement was all about H.O. Forged shortblock VS. SC forged shortblock, in which I'd say is in the 3.8s favor since its block is beefed up.

But that's what I'm saying though, regarding power splitting the 5.0 block before the internals. The block is usually what wipes them out in the process, at least in every case I've seen. Conversely though I still rarely hear failure of the 3.8 blocks themselves fatiguing to the point of splitting, like the 5.0s do. It's usually a rotating assembly failure. Plus like you said, neither presumably has the valvetrain to deal with it either.
 

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I dont even take my SC engine up to 5k RPM's .. after 3k the powerband drops off.

Plus the limitations are the Torque converter RPM if you are going Auto.
 

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I dont even take my SC engine up to 5k RPM's .. after 3k the powerband drops off.

Plus the limitations are the Torque converter RPM if you are going Auto.
After 3K? Is it a diesel?
 

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After 3K? Is it a diesel?
LOL, what ? It just doesnt make any difference .. by the time youre at 5k RPM's I could be in 3rd gear already ..

I need some larger valves in the heads / mild cam and some more OD on the supercharger, then I will take the RPM's up higher, but until then, 3k is perfectly fine.
 

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LOL, what ? It just doesnt make any difference .. by the time youre at 5k RPM's I could be in 3rd gear already ..

I need some larger valves in the heads / mild cam and some more OD on the supercharger, then I will take the RPM's up higher, but until then, 3k is perfectly fine.
It was just a joke. But to be making peak torque at 3K sounds like worn cams or something! I know being SC makes a difference, but still!

Whatever, like you said - it works fine for you and you're happy with it. That's all the matters, right? :thumbsup:
 

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It was just a joke. But to be making peak torque at 3K sounds like worn cams or something! I know being SC makes a difference, but still!

Whatever, like you said - it works fine for you and you're happy with it. That's all the matters, right? :thumbsup:
... yeah, factory rated 330 ft lbs torque at 2500 RPM, it doesnt make more torque any higher than that without changing things. ;)

NA is different, but once you get up to 5k RPM's your just making noise.
 

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Discussion Starter #12
Interesting tech. Also inquiring minds want to know.... are the 4.2 or split port heads and top end interchangeable with the older 3.8 stuff?
 

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NA is different, but once you get up to 5k RPM's your just making noise.
QFT! The 3.8 in the Cougar ... well, I'm almost embarrassed by the amount of noise it makes, even at about 3k. I've just accepted that it's a granny engine and quit trying to do things quickly. :D
 

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Discussion Starter #15
More good tech. Thanks, in my situation it would probably cost less to get an entire SC engine, however, this bird has to run on regular 87 octane pump gas... that's become my new restriction. This project will be the "peppy eco-box backup car" v6 bird. I'm just trying to find out what I can do to keep it from being a complete slug. My biggest hurdle is I have a distributor on this v6 and from what I've been reading this throws a wrench in the works for many split port swaps.
 

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More good tech. Thanks, in my situation it would probably cost less to get an entire SC engine, however, this bird has to run on regular 87 octane pump gas... that's become my new restriction. This project will be the "peppy eco-box backup car" v6 bird. I'm just trying to find out what I can do to keep it from being a complete slug. My biggest hurdle is I have a distributor on this v6 and from what I've been reading this throws a wrench in the works for many split port swaps.
Its not that bad with the distributor, you just have to be a little creative. I made it work with a e-150 fuel rail and custom EGR tubes. Oh btw mine passes Cali smog ;)
 

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Discussion Starter #17
Its not that bad with the distributor, you just have to be a little creative. I made it work with a e-150 fuel rail and custom EGR tubes. Oh btw mine passes Cali smog ;)
Also great info. As far as Emissions testing goes I'm very not concerned since I am a licensed Nevada emissions "smog" inspector. I'm sure I can get it running well enough to pass all by itself, we don't have those top end rebuild issues out here, just entire wrong engines, different blocks, etc...

So did you do the entire split port swap or just the top end?
 

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Also great info. As far as Emissions testing goes I'm very not concerned since I am a licensed Nevada emissions "smog" inspector. I'm sure I can get it running well enough to pass all by itself, we don't have those top end rebuild issues out here, just entire wrong engines, different blocks, etc...

So did you do the entire split port swap or just the top end?
Well if smog isn't an issue you can just block off the EGR port and get a tune. That would take care of one headache lol. I swapped a used engine from a '02 with about 80k on it. My old engine had a rod knock, but this one has a valve ticking noise when its cold so I might be doing another engine swap soon.
 

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Discussion Starter #19
Well if smog isn't an issue you can just block off the EGR port and get a tune. That would take care of one headache lol. I swapped a used engine from a '02 with about 80k on it. My old engine had a rod knock, but this one has a valve ticking noise when its cold so I might be doing another engine swap soon.
I'll go the legit route and have a custom EGR tube made, no issue there my exhaust guy is great lol.
 

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