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I am looking for some advice from those who build/use race engines. I currently have a 87 GXL, bone stock. It has about 120,000 miles on the original engine. Miraculously, it has compression numbers around 130 or so properly calibrated for speed and altitude. I would like to pull this engine at some point before it dies and rebuild it before something bad happens and trashes hard to get parts.
I do have a spare, ran when pulled S4 engine with roughly the same miles. I was considering rebuilding it, staying N/A with mods and going stand alone. However, with how hard the s4 parts are becoming to get, I think that I should buy something else like, a six port junk yard Renesis. Hoping to save good working unmodified S4 keg, etc.
I do realize that the lower intake of a Renesis will need either the stock ECU or Haltech. However with tech being what it is today, there might be aftermarket options for upper and lower intakes. Most likely not N/A though.
So, what would you do? Mod the S4 or save it? I know cost will be a big player here. Let's just put the cost issue toward the bottom of the worry pile and start there. Also, it would be nice to track the car at some point but also keeping it street legal. Thanks in advance for your thoughts.
(Just as a side note, I will likely be getting a RX8 six speed to pair with my extra 3.9 rear gear at some point, too.)
Yeah, it's certainly more likable than a likely noisy as hell partially ported N/A S4 for me, too at that HP. Not sure that I would want much more HP than stock.
There are rear end considerations, too. The 3.9 rear isn't ideal with over 200 HP and the RX8 gear box. The Axles will need upgraded, most likely.
Regardless of ultimate direction with the engine, I will likely pull the spare engine apart, clean everything, pack it up nicely and keep it at least until the original engine gets pulled.
Renesis all day for a street driven car. You’ll spend money and time building a loud FC engine that doesn’t make as much power as a stock port Renesis.
At 120k your engine probably has a lot of life left in it. The main issue to worry about IMO is a coolant seal land cracking out. This is an issue no matter which FC engine you use, so I wouldn't worry too much.
The S4 N/A intake manifold is a really good piece. I stuck one on a n/a Turbo II engine, after port matching and filling in the dead area where the aux ports would be, and picked up midrange AND top end. It pulled another 1000rpm at the dragstrip, I was shifting at about 9700 whereas with the TII manifold there was no point in going that high. Guesstimate 250hp at the crank, given its performance as compared to an engine that made a genuine 270hp.
[QUOTE][[color=#222222]Renesis all day for a street driven car. You’ll spend money and time building a loud FC engine that doesn’t make as much power as a stock port Renesis.
Wouldn’t go for a taller rear gear either./QUOTE]
I did some "testing" over the weekend. The 3.9 works better than expected. Thanks! How about strengthening mods? I have a LSD and have read where they wont last very long with more HP.
At 120k your engine probably has a lot of life left in it. The main issue to worry about IMO is a coolant seal land cracking out. This is an issue no matter which FC engine you use, so I wouldn't worry too much.
The S4 N/A intake manifold is a really good piece. I stuck one on a n/a Turbo II engine, after port matching and filling in the dead area where the aux ports would be, and picked up midrange AND top end. It pulled another 1000rpm at the dragstrip, I was shifting at about 9700 whereas with the TII manifold there was no point in going that high. Guesstimate 250hp at the crank, given its performance as compared to an engine that made a genuine 270hp.
There is another option though it's probably the most expensive one. If you go standalone while still on your current engine, you could go to a 13B-REW after that. A street ported n/a REW will make better power than a six port. 13B-REW parts are still available. There was a n/a 13b-RE built by Defined Autoworks making 230rwhp several years ago. Maybe someone with more knowledge can chime in but I don't know why an REW couldn't make similar numbers. I know the stock port sizing is different but after street porting I'm not sure if that matters. Maybe someone else knows. If the RE intake is the better choice, it will bolt to an REW if you can find one. They shortened the RE intake on this build. The reason I say REW and not the RE is the RE is hard to find and Mazdatrix now lists the irons as NLA
There is another option though it's probably the most expensive one. If you go standalone while still on your current engine, you could go to a 13B-REW after that. A street ported n/a REW will make better power than a six port. 13B-REW parts are still available. There was a n/a 13b-RE built by Defined Autoworks making 230rwhp several years ago. Maybe someone with more knowledge can chime in but I don't know why an REW couldn't make similar numbers. I know the stock port sizing is different but after street porting I'm not sure if that matters. Maybe someone else knows. If the RE intake is the better choice, it will bolt to an REW if you can find one. They shortened the RE intake on this build. The reason I say REW and not the RE is the RE is hard to find and Mazdatrix now lists the irons as NLA
The RE has much larger port runners on either the primary or the secondary (I forget which) than the REW. Given that the RE was a kind of intermediate step between the T2 and REW and was used in luxury cars, you would think that the REW would be an evolution geared more to ultimate power, but it seems the RE is the better engine to have especially if naturally aspirated.
I actually bought an RE keg for this purpose but found that someone had ported the intake ports deep into the oil seal track... no wonder it was cheap
That said the REW intake manifold looks like garbage and only exists in its form in order to make room for the turbos. Like the T2 intake manifold but worse. A decent Holley manifold or a dual sidedraft manifold would fix that right up, though. The stock runners seem to make a very sharp angle into the ports with no radius!
The RE has much larger port runners on either the primary or the secondary (I forget which) than the REW. Given that the RE was a kind of intermediate step between the T2 and REW and was used in luxury cars, you would think that the REW would be an evolution geared more to ultimate power, but it seems the RE is the better engine to have especially if naturally aspirated.
I actually bought an RE keg for this purpose but found that someone had ported the intake ports deep into the oil seal track... no wonder it was cheap
That said the REW intake manifold looks like garbage and only exists in its form in order to make room for the turbos. Like the T2 intake manifold but worse. A decent Holley manifold or a dual sidedraft manifold would fix that right up, though. The stock runners seem to make a very sharp angle into the ports with no radius!
It was my understanding that the REW's intake ports are angled which helps with the bend the intake makes to clear the turbos. At least making it an improvement over the TII. That said maybe a decent Holly manifold and a 4150-style throttle body is the way to go for a n/a REW build. How do the Holley manifolds compare to one that uses Weber style throttle bodies as far as power is concerned? I was thinking they are close.
The RE has much larger port runners on either the primary or the secondary (I forget which) than the REW. Given that the RE was a kind of intermediate step between the T2 and REW and was used in luxury cars, you would think that the REW would be an evolution geared more to ultimate power, but it seems the RE is the better engine to have especially if naturally aspirated.
I actually bought an RE keg for this purpose but found that someone had ported the intake ports deep into the oil seal track... no wonder it was cheap
That said the REW intake manifold looks like garbage and only exists in its form in order to make room for the turbos. Like the T2 intake manifold but worse. A decent Holley manifold or a dual sidedraft manifold would fix that right up, though. The stock runners seem to make a very sharp angle into the ports with no radius!
you're not wrong, but the turn the REW intake takes into the engine is the same as the T2 and Cosmo. they just tilted the whole thing, port runners and all
Thanks for the input everyone. An RX8 keg at least looks like the way to go.
Since we are here, I was able to tear down my spare engine, with about 128,000 miles, to the keg, front cover and flywheel. I added the auto trans bell housing and a starter. I was able to get a compression test completed. I added some two stroke to the inside of the engine, filled the oil that likely turned to sludge in the last years. I got about 105 on the faces, no real variances to worry about. The antifreeze was drained when the engine was pulled. When I pulled the lower bolt a very small puddle came out completely clean.
If I sell this eventually or am forced to use the engine, I would be temped to just use it as is, minus the front cover gasket and wearable stuff behind it, oil pan gasket and similar items like the rear seal if accessible from the outside. There does appear to be some oil leak at the rear seal, too.
Would you do a full rebuild with new seals, etc or just the easy stuff?
Thanks for the input everyone. An RX8 keg at least looks like the way to go.
Since we are here, I was able to tear down my spare engine, with about 128,000 miles, to the keg, front cover and flywheel. I added the auto trans bell housing and a starter. I was able to get a compression test completed. I added some two stroke to the inside of the engine, filled the oil that likely turned to sludge in the last years. I got about 105 on the faces, no real variances to worry about. The antifreeze was drained when the engine was pulled. When I pulled the lower bolt a very small puddle came out completely clean.
If I sell this eventually or an forced to use the engine, I would be temped to just use it as is minus the front cover gasket and wearable stuff behind it, oil pan gasket and similar items like the rear seal if accessible from the outside. There does appear to be some oil leak at the rear seal, too.
Would you do a full rebuild with new seals, etc or just the easy stuff?
At 105psi, that’s a pretty healthy spare. You could go either way. It would likely be a good candidate for either a full rebuild or throw new gaskets on and run it for a few years while you build another.
