LS4 / F40 swap - fieroguru (Page 8/216)
ckrummy JAN 07, 02:58 PM
I'm just gong to say that if there are any larger gaps when welding aluminum i suggest MIG because it is easier to bridge the gaps especially on cast aluminum. If your going to TIG make sure the gaps are tight and clean or its just going to burn away.
stickpony JAN 07, 03:48 PM

quote
Originally posted by fieroguru:


I haven't taken either of my F40's apart to see how difficult the change would be. If all the gears are seperate and not integrated into the shafts, then it would be much easier. I would love to have either a 3.0 final drive or a 3.0 first gear... but either of those would probably double the cost of this swap, so I will be sticking with the stock ratios.

Knowing the ratios are what they are, my engine was built to rev and I am planning to shift at 7000 rpm. This makes 1st gear last till 38mph and 2nd till 71 with a 24.6" I could gain a few more MPH in each gear by going to a slightly larger diameter wheel/tire package.



what mods were done to make it rev more freely?

a simple final drive change would be affordable enough i would think.. the 1st gear is going to be a bit more difficult
fieroguru JAN 07, 06:54 PM

quote
Originally posted by stickpony:


what mods were done to make it rev more freely?

a simple final drive change would be affordable enough i would think.. the 1st gear is going to be a bit more difficult



Spinning it to 7K and making power to 7K are two completely different issues. The LS(x) engines are quite strong and just need good rod bolts and a stabile valve train to pull to 7K. To make power at that RPM requires a low restriction intake/exhaust combination with an appropriate camshaft.

For my swap I have upgraded: MAF, Throttle body, Intake, Injectors, camshaft, valve springs, exhaust and tune. The DoD lifters are probably the weakest link and the stock 2007 rod bolts next. The nice thing about the LS4 is if/when I blow the engine, for $1000 I can have another and swap my parts to it and do it again.

Until you pull the transmission apart and take a look at the individual gears and shafts, it is unknown as to which would be cheaper to swap (1st or the final drive). If the pinion gear to the final drive is intergral (or cut directly into) to the output shaft then making that shaft/gear setup becomes costly (and remember you need 2 of them due to the 3 shaft design). If the 1st gear is integral to the shaft, or common to 2nd gear, then that setup becomes more difficult and expensive... won't really know what you are up against until you disassemble the transmission.

[This message has been edited by fieroguru (edited 01-07-2011).]

blackrams JAN 07, 07:00 PM

quote
Originally posted by fieroguru:

The nice thing about the LS4 is if/when I blow the engine, for $1000 I can have another and swap my parts to it and do it again.



Paul,
As I told you today on the phone, there is a fine line between genius and insanity. You're way over that line.
One of the reasons I like you and your work.

Ron
fieroguru JAN 07, 07:08 PM

quote
Originally posted by blackrams:


Paul,
As I told you today on the phone, there is a fine line between genius and insanity. You're way over that line.
One of the reasons I like you and your work.

Ron



Guilty as charged! Thats why Sara has a masters degree in psychology...
dobey JAN 07, 08:32 PM

quote
Originally posted by fieroguru:
For my swap I have upgraded: MAF, Throttle body, Intake, Injectors, camshaft, valve springs, exhaust and tune. The DoD lifters are probably the weakest link and the stock 2007 rod bolts next. The nice thing about the LS4 is if/when I blow the engine, for $1000 I can have another and swap my parts to it and do it again.



You're not going with the ARP rod bolts?

As far as the lifters go, from what I'm finding on other forums asking about their reliability, I would stay under 6200. Seems like their weight and design will lead to much higher chance to break after that.
1fatcat JAN 07, 10:17 PM

quote
Originally posted by stickpony:

as it sits, the 1st gear(3.77:1) combined with the final drive(3.55:1) gives a combined ratio of 13.38:1. that is outrageous behind a v8 man! you would be shifting after barely touching the gas...with the average fiero tire size, you would be shifting around 25 mph....dropping both the 1st gear and the final drive to something around 3:0:1 would of course be ideal

so is this something that is doable??




Not easily. The F40 uses an input shaft and 2 main shafts. The main shafts BOTH enguage the differential gear (the equivalent of a ring gear in a RWD differential) at all times. To change the final
drive ratio, you would have to change the diff gear and both of the shaft gears. 1st gear is part of one of the main shafts, and 2nd gear is part of the other main shaft. So to change the ratio of 1st or second, new shafts would be needed at the very least, and they would be very expensive...if you could even find someone willing to make them?
fieroguru JAN 08, 08:00 AM

quote
Originally posted by dobey:


You're not going with the ARP rod bolts?

As far as the lifters go, from what I'm finding on other forums asking about their reliability, I would stay under 6200. Seems like their weight and design will lead to much higher chance to break after that.



I haven't purchased or installed the rod bolts yet. Still kicking around going with Katec vs. ARP. I am planning to install them once I take everything back apart to paint it. The rod bolts and clutch are the last significant purchases for the build I still need to make.
dobey JAN 08, 12:44 PM

quote
Originally posted by fieroguru:
I haven't purchased or installed the rod bolts yet. Still kicking around going with Katec vs. ARP. I am planning to install them once I take everything back apart to paint it. The rod bolts and clutch are the last significant purchases for the build I still need to make.



I didn't know Katech had rod bolts, but now that I see they do, and see the specs vs. the two different ARP bolt versions, I would still go with ARP. Even the more expensive ARP 2000 bolts are still only about $100, while the Katechs are $200. Is there something special about the Katechs that would make them worth the extra $100? The ARPs seem to be stronger, as far as I can tell from the specs.
fieroguru JAN 08, 07:09 PM

quote
Originally posted by dobey:
I didn't know Katech had rod bolts, but now that I see they do, and see the specs vs. the two different ARP bolt versions, I would still go with ARP. Even the more expensive ARP 2000 bolts are still only about $100, while the Katechs are $200. Is there something special about the Katechs that would make them worth the extra $100? The ARPs seem to be stronger, as far as I can tell from the specs.



Katech rod bolts have a yield strength of 260,000 psi and ARP 2000 is 220,000 psi. Katech's are able to be installed w/o resizing the large rod end... which is desirable when swapping the bolts w/o engine disassembly. ARP still specifies to resize the rods when used which would require engine disassembly (sure many have done it w/o resizing w/o issue, but there have been several reports from those people about spinning bearings). Lastly, Katech was involved in R&D/durability testing for the GM LS1 ASA engines and developed and proved the capabilities of their rod bolts during that testing.

I will probably go with the Katechs and have one less chance of failure.

The LS4/F40 is back on the cradle fixture so I can fab up the mount tabs... but it will be a week or two till it get back to it... busy parting out a 2.8/Getrag to help pay for the next round of parts.