TweakGames

iTrader: (3)

I am on the war path looking for an LSx to swap into my FC, and doing tons of research to find all the problems I should expect to run into. I was comparing dynos and such, when I found something interesting. It seemed, as though the stock ls1 dyno, matched my t04s's 11 psi dyno almost ..... perfectly, just 1500 rpm earlier.

For a graphical explanation, here is a flash animation I made and uploaded comparing the two graphs.

http://www.youtube.com/watch?v=YLLSo3LM7jo

bbaaddd quality utube.

u can download higher quality clip here. (2.6 mb)
http://postdownload.filefront.com/13...c382d19086de9f

Sometimes, I get carried away, and want to make sure I am looking at both sides of this reasonably. Other than the argument that I will destroy the soul of my rx7, are there any logical reasons I really shouldn't? From what I have found or thought up for my specific situation:

LS1 swap:
Pros:
- Same Power and power curve as my last build, just 1500 rpm sooner
- More reliable as I won't be requiring a turbo, all the required turbo components, or high rpm to reach 300 rwhp.
- any decent tuner can tune it, I get second chances when I start to knock hehe.
- more mellow exhaust noise should keep the cops off my butt
- car shouldn't smell like two somewhat jaded beavers crawled into my muffler and had 3 sets alien twins that consisted entirely of fuel, oil, new born baby excretion.
- better mpg (don't really care about that, but ok)
- it's not as heavy as everyone things. I think having our huge turbo, manifold, intercooler and such make it quite equal.
- I will be controlling the ls1 with my e11v2, and using a IQ3 dash (that uses GPS for speedo and such) so I won't need to worry about hooking up any of the stock gauges or anything like that.

Cons:
- Most the people on this forum will hate me. :/ If you have met me you know I don't care what you think.
- Initial cost
- I don't know squat about piston engines, (but then again I didn't know anything about rotary engines when I started)

I am tired, so I am sure there are more. Please feel free to add on. Please keep it logical, and not that I am a rotary killer, because the rotary engine has killed my hopes and dreams more than you could ever imagine. lol.

~Tweak

bosscobra

iTrader: (1)

youve got my vote, haha, and remember hp= tq x rpm/5250, lol

TweakGames

iTrader: (3)

lol glad to see something got through. Tell your mom there is still hope for you!

Josh18_2k

iTrader: (3)

you really dont need to know anything about piston engines. how-to's for every bolt on are laid out clearly online with pics (ls1howto.com is a good one). and if you leave it stock.. well just change the oil and drive it for years.
my car has been on the road for 20k miles now, and the only thing i've done to the engine is replace the alternator after i dipped it in a really big puddle.

Upgrayedd

iTrader: (1)

The handling benefits are actually still in your favor with the LS1 cuz it's so lightweight for such a large motor. Not to mention throw on a decent exhaust and intake and you'll beat mort lol

mort2002

iTrader: (1)

Hey hey, how did i get drug into this and BTW im not done yet...
i have a mani and a holset hx40 sitting in my kitchen right now.

zack4173

iTrader: (3)

This is such a tuff decision to make really. The benefits of the LS1 are hard to see many negatives in it. That being said its equally as hard getting rid of the rotary especially for guys like us that love it so well. So I will just say good luck and cant wait to see the car when its done regardless off which way you decide to go.

TweakGames

iTrader: (3)

I am still excited to see how that turns out for you. I think you will be VERY happy.
I have no clue how you got drug into it too lol. Was funny though.


Yeah, I .... have issues with the swap also. I normally consider myself a VERY logical person, a brain that is very far from working off emotion instead of facts and common sense. Like you said, hard to see many negatives to an LS1 swap.

Looking back at it, I got the most fun at beating cars that I should not have beaten with my old FC 1.3L. The looks on BMW owners faces, the feel of (at what I thought) of a unique rotary power curve, the fact that I built something that can go toe to toe with some faster stock cars for somewhat cheaper.... all pretty great times. But after adding up all the time..., money..., stress (angry GF lol), research, ect I needed to have the feeling of beating someone with a smaller engine ... just kinda seems silly now. I feel like even if I win a race, I still lost...

I guess the problem is that people think you are cheating, or you are less of a man not keeping the rotary engine, but who makes these rules? Why do we constantly come to a gun fight with a knife (a pimped out boosted shiny knife) just to say we won the fight with just a knife? If starting off with a disadvantage is what is "cool" then why not show up blindfolded with two semi frozen turkeys as boxing gloves? The rotary world is an interesting one, people get praised for putting in a single turbo 20B, but looked down on for installing anything else. I used to feel the same way, never quite understood why. I think all rotary people are just hoping that someday, some random person that has stuck with the rotary engine is going to wake up, and invent something that will make the rotary engine the best, most reliable engine ever.... I hope it happens, I really do, but...

This has been me trying to justify putting in an LS1, thank you for listening. I seriously would like it if someone could give me some reasons to not though. I know it can't ALL be positive to put an LS1 in. :P


Here are a few pictures from the video above in case you can't see what was going on, or you can't open the video.

Here is a stock LS1 dyno.



Here is my cleaned up 13b-RE T04S 11 psi dyno.



Here is them lined up on the same HP / TQ / and RPM scale. (Green lines represent how much later in the RPM range the rotary made the same HP as the LS1. The blue line is rotary HP, the thick red is rotary TQ. The high thin red line is LS1 TQ, the / angle thin red line is LS1 HP. )



Here is to show the LS1 has the same HP curve as my engine. I did this by keeping the same scale just moving the LS1 dyno to the right.



Same thing but with a thicker (only 10 HP thick) green line over the horsepower curves showing how they are so much identical, they are almost completely hidden.



It looks like my RE is just a much more complicated, moody, and laggy LS1 lol.

If anybody is confused on how this is possible, or doesn't quite understand how HP is calculated, I will be happy to explain. I find a LOT of people are completely off when talking about HP and TQ. It's quite entertaining to listen to people explain how they got these new part that seemed to raise the torque but lower the HP at the same RPM. Want to slap em. Also to make it clear, the LS1 dyno drops off hard at 2200 rpm because that is where the person went from little to no throttle to full throttle. It does not mean the engine can only produce 25 TQ and 10 HP at 2100 rpm lol.

Anyways.... keep the convo up. I love educated debates.

~Tweak

Upgrayedd

iTrader: (1)

Sorry mort couldn't resist starting a feud lol Just had to throw out some funny. Honestly Tweak there are more pros then cons to the LS1 swap, the main con is it isn't an LS7

TweakGames

iTrader: (3)

Lol, I'm starting to see that. I'm opening a whole new can of worms. With our rotary engines, we were limited to around 400 rwhp and ~14 psi because of pump gas and going over that can cause, .... reliability issues lol ...... I'm pretty sure a modified ls1 or other version of the lsx engine are able to make much more than 400 on pump gas.

JordanRykon

iTrader: (1)

Tweak, find someone with an LSx and ask if you can drive it and compare for yourself, numbers might be the same but what if you do the swap and you dont like the feel or the responsiveness compared to your old setup?

I'm not saying your not researching this or anything I'm just saying my friend has gone through having a 350 v8 to a crazy boosted sr20 and now hes gone to a fully built 383 thats puttin out 400 to the wheels. It comes down to what you really enjoy driving and will want to continue driving for a while or until you find something else of interest. I've driven a 600 horsepower supercharged mustang lol talk about shittin your pants fast. V8's in general have almost endless possibilities with the right funding and inspiration

somethin to think about tweak.. good luck with your project hope its what your lookin for

Fumi

this "chat" is going well so far guys please keep it that way

ehime

iTrader: (18)

Well Fumi, that's because some of us like pistons too
Usually the bad chats start with people who posses more
'respect' and little knowledge. Our PNW region has
quite a few people who've already strayed from rotaries.
It's good to keep the possibilities open imho.

So Tweak you planning on building an LS in the background
and swap when your RE goes ****? Or are you planning on
yanking your engine and going at it now? Congrats btw, I
remember talking to you not so long ago about you wanting
to go LS, nice to see you finally moving on it.

Oh and had another quick question, do those RacePak IQ3
dashes have integrated data logging or do you need to buy
a separate logger for it?

zack4173

iTrader: (3)

As far as Im concerned I would like to have both an LS1 FD and a 13B or 20B FD eventually its like having two different cars for me.

JordanRykon

iTrader: (1)

^ In a perfect world right zack haha

rotary-guy

iTrader: (24)

iv been thinkin bout doin the same thing to one of my shells thats laying around, but id be using a 302 seeing how i have a few of them kicking it around my shop.

i like looking at this site http://hinsonsupercars.com/s-2-mazda-rx7-fc-86-92.aspx
it has a lot of the stuff u will be needing too.

Josh18_2k

iTrader: (3)

that stock ls1 dyno is pretty weak.. probably because of the OEM camaro exhaust/intake
heres mine with stock manifolds and cats, and the typical open element intake setup.

TweakGames

iTrader: (3)

Hmmm.... They seem prettttty dang close to me. Just a little 10-12 hp difference towards the redline.
Here is a picture of the dynos layed over on each other.





At least we know the engines are consistent.

TweakGames

iTrader: (3)

I just noticed also that the stock ls1 (red graph) isn't level. It slopes down just a little bit. (opps) Looks like a good 1 - 2 hp/tq loss lol. Gasp!

mort2002

iTrader: (1)

Sounds like you have convinced yourself to go to a LS1 now...
i see the benifits though...
i was working on my stupid piston car all weekend.. damn that oil pump and oil pan gakset!!!

Hyper4mance2k

iTrader: (40)

Cons:
LS1 is heavier than a 13bt, so your FC will not be as balanced.57/43 instead of 51/49.
Also The LS1 will sit over the front crossmember instead of behind it like the 13b does adding more weight infront of the front wheels making the car push more and more unbalanced no matter how light it is. Even if it's only 50 more lbs than the 13B puttinf the weight infront of the wheels will slaughter the balance you're acustomed to. Not to mention that the LSI carries 80% of it's weight in the top half of the engine with teh heads and intake manifols and such. Raising your center of gravity.
However, (Pro)
You don't race your car in any scantioned events that I know of, so I don't think you really care. The tiniest of balance changes won't make you less competitive on the street or on the Dyno.

WingsofWar

the difference between the LSX vs 13B is like nearly night and day. Even when the numbers are the same on the dyno the difference between the two engine really could only be felt with your hands on the steering wheel and the foot on the gas.

Your most definitely going to need to get your suspension and drivetrain dialed in to accept the engine. Especially if your trying to use the car for multiple types of racing.

But you know my take tweak on the LSX, id say do it. Also reliable power attracts me far more than anything else really.

Good luck!

Josh18_2k

iTrader: (3)

http://www.v8rx7forum.com/v8-rx7-tec...tml#post489289
http://www.v8rx7forum.com/v8-rx7-tec...ast-night.html
^ that one is LT1 (iron block)
http://www.v8rx7forum.com/v8-rx7-tec...3-ls1-fcs.html
and the most front heavy car i've come across:
http://www.v8rx7forum.com/v8-rx7-tec...r-weights.html
he has all the weight adding stuff in front, and no spare.

TweakGames

iTrader: (3)

In response to:
Hyper4mance2k - I agree either everything you said. Things are going to be different, but I am not doing any serious omg im .1 seconds slower time attacks, it won't really be that big a deal. I do "think" there will be a difference, but it's not like I was pushing my FC to the edge anyway with my 2 years of 0 professional alignment while switching through 3 different sets of suspension. lol I installed my stance coilovers recently and they are amazing, if the car feels even close to what it did before the LSx swap with coilovers unaligned, as with an LSx engine and an alignment and corner wight, I will be more than a happy camper. I will be a happy hiker, or even a happy paraglider.

Also, I was rocking a NA steel hood .... for some reason ... not quite sure why. Can't get a lot of weight much higher and forward than that.

WingofWar - If you know of someone with an lsx rx7 swap, or I guess even an lsx motor in general (lol) that would let me ride or go for a spin, that would be amazing.

Josh - thanks for the information. You are being extremely helpful.

~Tweak

Rx7TyreBurna

iTrader: (1)

An LS1 motor swap is very interesting. I've thought about it, but I am more into autoX and have heard, but haven't actually seen, that the LS1 swap unbalances the car like crazy.

Power wise, i don't think there is any comparison. N/A 13B vs. N/A LS1.

If you ever get a chance to go down to the track, I would love to hear how it handles.