why such differing numbers on the 3800 hp numbers, i've read and searched and ... (Page 1/3)
ttt123 JUN 21, 11:25 AM
So I've spent the last couple of days reading and reading and reading up on the 3.8sc series two swap as I have a fiero with a stock swap done and I'm getting ready to do the same swap into my 911 but with a built motor.

There seems to be so many differing claims on horsepower... why is this? that's a question coming from the view point of someone who is being genuine and not sarcastic. I can build a motor all day long(worked in machine shops my whole career) but the hp recipes and tuning and all the technically stuff outside of physically building a motor I've always been lost...mental block or something lol

I've read a ton of threads on this site and most of them turn into arguments on stock hp and hp after mods and so on and so on. I know this topic has been beaten to death but was just hoping some of the gurus(some of you have been on this thread for a loonnnggg time and know your stuff) would chime in and clear it up some for this

the 1/4 miles list I seen sure seems to have some fast fieros on it .. is it torque.. is it hp.. if this motor built is only putting down around 250whp from what I'm reading how are they being so fast? what am I missing. my motor is basically tall stack intercooler, xp cam, #60 injectors, north star tp, ported EVERYTHING, 3.2 pulley, headers and true dual exhaust. is that really only going to make about 250whp? my 911 now makes 298hp and 258 torque.. not that impressive but I bet if I rolled up on a built 3.8sc fiero... it would smoke me from the youtube vids I've seen. mine runs poopy right now and completely stock so I haven't been able to race it against my 911 yet lol

my 911 should be in the same ball park as the fiero for weight and engine is in the rear like a fiero... I'm just trying to understand better what I'm doing, if this annoys anyone... sorry, just curious lol
Will JUN 21, 01:10 PM
I'm curious... which 911? 996? I've heard of LS and Audi V8 swaps, but not a 3800 swap yet.

There are always rules of thumb for how much power you might expect from a given set of mods, but you never know until you get it on the dyno. There are also variables like whether the trans is a stick or automatic, what the stall speed is, etc.

Also, the engine's almost guaranteed NOT to be making best power if it hasn't been tuned in some way. On the dyno is best, then the dyno operator will give you a dyno sheet. You'll know that your tune is good for your engine AND you'll know how much power it's making. You wouldn't swap out stock manifolds for headers without rejetting the carb, would you? The same applies to fuel injection. When you make hardware changes, you have to tune the computer to make the best use of them.

The supercharged 3800's are good for an instant hit and highly responsive when you mash the gas, especially in the low RPM. However, the cars making big power have turbos and do not have superchargers.
ttt123 JUN 21, 01:44 PM

quote
Originally posted by Will:

I'm curious... which 911? 996? I've heard of LS and Audi V8 swaps, but not a 3800 swap yet.

There are always rules of thumb for how much power you might expect from a given set of mods, but you never know until you get it on the dyno. There are also variables like whether the trans is a stick or automatic, what the stall speed is, etc.

Also, the engine's almost guaranteed NOT to be making best power if it hasn't been tuned in some way. On the dyno is best, then the dyno operator will give you a dyno sheet. You'll know that your tune is good for your engine AND you'll know how much power it's making. You wouldn't swap out stock manifolds for headers without rejetting the carb, would you? The same applies to fuel injection. When you make hardware changes, you have to tune the computer to make the best use of them.

The supercharged 3800's are good for an instant hit and highly responsive when you mash the gas, especially in the low RPM. However, the cars making big power have turbos and do not have superchargers.



yes 996 link to a QUICK snipit of the build https://www.youtube.com/watch?v=G4keZmwYpss its had an article written about it and its quite a fun car there is a few videos on the car in my channel along with a build thread link in the description under the video. The Audi v8 and ls swaps are popular but they are very expensive. the ls swap is a guaranteed $20k As far as I know(I've searched lol) I'm the first to swap in the 3.8. I have already had the custom adaptor kit made and have purchased everything to do the swap. I also have all the stuff to do a chevy v8 swap but .. I want to be different lol Just an fyi.. this swap to a Porsche manual 6speed tranny would fit in a fiero if anyone was interested.

I do have someone lined up for the dyno tune. I also have a pair of new in the box GT35 turbo's on my shelf but like mentioned in the first post.. I'm just not very technically skilled for figuring out the engine side of this stuff vs the fabrication and body work. so I figured doing a supercharged 3.8 vs a turbo will be easier. I can always upgrade to the turbos down the road.

I'm trying to make sure I do all the supporting mods for the parts I'm buying I was just a little confused on the confusing results from all the builds I've been reading about over the last few weeks. I was under the impression this set up would consistently produce about 400 bhp not that the hp is everything as I can see how quick these motors are watching the youtube vids. my stock 3.8sc fiero the couple times I've driven it wasn't that impressive but it is bone stock and doesn't look anything like the built ones I've seen.

ttt123 JUN 21, 01:45 PM
forgot to mention .. I'm all in as of right now at Just over $5k
FIER086 JUN 23, 07:41 PM

quote
Originally posted by ttt123:

So I've spent the last couple of days reading and reading and reading up on the 3.8sc series two swap as I have a fiero with a stock swap done and I'm getting ready to do the same swap into my 911 but with a built motor.

There seems to be so many differing claims on horsepower... why is this? that's a question coming from the view point of someone who is being genuine and not sarcastic. I can build a motor all day long(worked in machine shops my whole career) but the hp recipes and tuning and all the technically stuff outside of physically building a motor I've always been lost...mental block or something lol

I've read a ton of threads on this site and most of them turn into arguments on stock hp and hp after mods and so on and so on. I know this topic has been beaten to death but was just hoping some of the gurus(some of you have been on this thread for a loonnnggg time and know your stuff) would chime in and clear it up some for this

the 1/4 miles list I seen sure seems to have some fast fieros on it .. is it torque.. is it hp.. if this motor built is only putting down around 250whp from what I'm reading how are they being so fast? what am I missing. my motor is basically tall stack intercooler, xp cam, #60 injectors, north star tp, ported EVERYTHING, 3.2 pulley, headers and true dual exhaust. is that really only going to make about 250whp? my 911 now makes 298hp and 258 torque.. not that impressive but I bet if I rolled up on a built 3.8sc fiero... it would smoke me from the youtube vids I've seen. mine runs poopy right now and completely stock so I haven't been able to race it against my 911 yet lol

my 911 should be in the same ball park as the fiero for weight and engine is in the rear like a fiero... I'm just trying to understand better what I'm doing, if this annoys anyone... sorry, just curious lol



You"ll make much more than 250whp with that setup.

Just for reference my setup is in my signature and I had it dyno tuned by ZZP. I made 290whp and 320tq and I have a sheet to prove it. I have since put a 3.2 pulley on but have not dyno'd yet. Probably at 300whp now. I bet with your setup and proper tune you'd see atleast 350whp.

Good luck!

------------------
'87 GT - 5spd, Project Car- 3800SC II: Full Rebuild, VS Cam, 90# Springs, 3.3 pulley, TOG headers, 3.5" CAI, WP underdrive pulley, A104's, 180* thermostat, 36lb injectors & SPEC 3+ clutch- 38SP3CL: 290whp @ 320 lb/ft

'86 SE 2m4: my first car at 16- SOLD
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fieroguru JUN 23, 07:59 PM
It all comes down to the details.

Components used, quality of the installation, quality of the tune, margin of safety in the tune, dyno type use, correction factor used on the dyno, and other factors that impact RWHP numbers (like running large diameter & wider wheels and tires).

Dynos are only good for tuning in a safe environment and evaluating the effectiveness of the upgrades, but you have to do before and after runs on the same dyno and as close to the same ambient temps as possible. You can't say that your dyno sheet is 10 hp higher, so your car is faster or will do better in the 1/4 mile.
ttt123 JUN 23, 08:47 PM

quote
Originally posted by FIER086:


You"ll make much more than 250whp with that setup.

Just for reference my setup is in my signature and I had it dyno tuned by ZZP. I made 290whp and 320tq and I have a sheet to prove it. I have since put a 3.2 pulley on but have not dyno'd yet. Probably at 300whp now. I bet with your setup and proper tune you'd see atleast 350whp.

Good luck!



That’s encouraging to hear. Your in grand rapids, if your ever up for a cruise id love to see your car. Im over in lapeer right off I-69.

ttt123 JUN 23, 08:52 PM


quote
Originally posted by fieroguru:

It all comes down to the details.

Components used, quality of the installation, quality of the tune, margin of safety in the tune, dyno type use, correction factor used on the dyno, and other factors that impact RWHP numbers (like running large diameter & wider wheels and tires).

Dynos are only good for tuning in a safe environment and evaluating the effectiveness of the upgrades, but you have to do before and after runs on the same dyno and as close to the same ambient temps as possible. You can't say that your dyno sheet is 10 hp higher, so your car is faster or will do better in the 1/4 mile.



Understood, i’ve tried to buy all the supporting parts i could to support the build. I’ve followed the recipe of some builds and i do have arrangements for a good dyno tune. I dont plan on pushing it as hard as i can with the tune, im ok leaving a little on the table to keep it a little more reliable.

Thanjs for the input.. very appreciated.
La fiera JUN 23, 10:09 PM
I used to work at a Porsche specialty shop in Maryland back in 2001and some dude wanted a 6.5L/400CI Small Block Chev in his 911!
That was a piece of pupu. The nimbleness was lost and it felt like the car was carrying the Caribean Royale's ancher.
With a customer's 912 which is a 911 with a flat 4 bettle engine I had to wait for him on the winding roads. After a couple
of these runs he got the point. Straight line speed and power means nothing. I could've beat him with a 800cc Yugo on the twisties
because he didn't know how to drive that car. I've outrun a lot of Mustangs 5.0's on the winding roads here in NC, so personally I'd
take the lesser of the two wissels.
ttt123 JUN 24, 05:33 AM

quote
Originally posted by La fiera:

I used to work at a Porsche specialty shop in Maryland back in 2001and some dude wanted a 6.5L/400CI Small Block Chev in his 911!
That was a piece of pupu. The nimbleness was lost and it felt like the car was carrying the Caribean Royale's ancher.
With a customer's 912 which is a 911 with a flat 4 bettle engine I had to wait for him on the winding roads. After a couple
of these runs he got the point. Straight line speed and power means nothing. I could've beat him with a 800cc Yugo on the twisties
because he didn't know how to drive that car. I've outrun a lot of Mustangs 5.0's on the winding roads here in NC, so personally I'd
take the lesser of the two wissels.



I big part of these swaps is the hieght of the weight..if that makes sense. The flat six is pretty much the same weight as the 3.8sc but its center ois taller. Like a boat that sticks up higher out of the water. I will loose a little cornering but i think it wont be crazy like a 400cid. Plus the pick up in power i think will make it worth with a still pretty good handling car. I race mine at the track now and then but for the most part.. its a nice day drive it to work car.