6-port w/S4 turbo....247whp @ 8 psi through a cat
12-21-05, 04:55 AM
#1
6-port w/S4 turbo....247whp @ 8 psi through a cat
To begin, this whole project actually takes place on a 1st Gen GSL-SE but the relavence is that it is a 6-port 13B. I'm posting this here to help motivate those interested in doing a turbo install on any 6-port NA engine. The upgrade path is similar regardless of generation. For details on the project check out this thread... https://www.rx7club.com/forum/showthread.php?t=471912
The cliff notes are that we installed a stock S4 turbo and manifold on a completely stock GSL-SE. The -SE has a compression ratio of 9.4:1 just like the S4 NA. The -SE does have 3mm apex seals stock so that is a blessing to boost. The rotating assembly is slightly heavier than that of the S4 but otherwise the engines are functionally very similar. This engine has about 140,000 miles on the clock but is in remarkably excellent shape. A pre-op compression test showed over 120psi on all faces of both rotors.
We installed an S5 NA intake. We did this for a couple reasons. The most obvious is to gain easy installation of a pair of secondary injectors. The -SE only uses one pair of injectors in the primary location. The S5 manifold also flows much better than the -SE piece. We looked at adapting the TII manifold but that would of required a good deal of fabrication. The ports don't line up well at all as you can see in the pic below. The only downside of using the NA manifold is that the charge pipe ends up being a bit longer. With the small stock turbo spool is still extremely quick.
The only problem we ran into outside of the usual 2nd Gen install was the tighter spacing of the frame rail on the 1st Gen. This meant that we had to cut down the LIM to gain clearance. The six-port actuators we hacked off as was the ACV. The resulting holes were welded up, ground flush, and the entire assembly media blasted so that it looks factory fresh. IMO this is a good mod just from an ethetics standpoint. It really cleaned up the look of the stock manifold.
The exhaust at this point consists of a 3" downpipe running to a Magnaflow 16" catalytic converter. We haven't had a chance to finish the rest of the exhaust. Why a cat you ask? To control boost. The cat was an after-thought. With a generously ported wastegate we were still seeing boost spike to 14psi instantly when the turbo began to spool running an open downpipe. We wanted to limit boost to 10psi. The cat was a simple, effective, inexpensive solution. It works. Adding a restriction to the exhaust stream is not the best idea. A better wastegate would be ideal. But within the confines of a budget the cat works excellently. We can also say we're being environmentally friendly too. With the cat the boost spikes to 10psi on initial spool then settles to 8psi where is holds until the power falls off past 7k rpm.
For engine management the owner decided on an E6X. We added 1600cc injectors for secondaries and used the stock -SE injectors for primaries. The 1600s are overkill for now but the owner has plans for a full TII/T4 upgrade down the road.
The end results with a minimum of tuning was 247whp and 232lb/ft at a sustained 8psi. So far any of you who are considering turboing an NA engine it can be done, done effectively, and can make good power with a conservative tune.
The cliff notes are that we installed a stock S4 turbo and manifold on a completely stock GSL-SE. The -SE has a compression ratio of 9.4:1 just like the S4 NA. The -SE does have 3mm apex seals stock so that is a blessing to boost. The rotating assembly is slightly heavier than that of the S4 but otherwise the engines are functionally very similar. This engine has about 140,000 miles on the clock but is in remarkably excellent shape. A pre-op compression test showed over 120psi on all faces of both rotors.
We installed an S5 NA intake. We did this for a couple reasons. The most obvious is to gain easy installation of a pair of secondary injectors. The -SE only uses one pair of injectors in the primary location. The S5 manifold also flows much better than the -SE piece. We looked at adapting the TII manifold but that would of required a good deal of fabrication. The ports don't line up well at all as you can see in the pic below. The only downside of using the NA manifold is that the charge pipe ends up being a bit longer. With the small stock turbo spool is still extremely quick.
The only problem we ran into outside of the usual 2nd Gen install was the tighter spacing of the frame rail on the 1st Gen. This meant that we had to cut down the LIM to gain clearance. The six-port actuators we hacked off as was the ACV. The resulting holes were welded up, ground flush, and the entire assembly media blasted so that it looks factory fresh. IMO this is a good mod just from an ethetics standpoint. It really cleaned up the look of the stock manifold.
The exhaust at this point consists of a 3" downpipe running to a Magnaflow 16" catalytic converter. We haven't had a chance to finish the rest of the exhaust. Why a cat you ask? To control boost. The cat was an after-thought. With a generously ported wastegate we were still seeing boost spike to 14psi instantly when the turbo began to spool running an open downpipe. We wanted to limit boost to 10psi. The cat was a simple, effective, inexpensive solution. It works. Adding a restriction to the exhaust stream is not the best idea. A better wastegate would be ideal. But within the confines of a budget the cat works excellently. We can also say we're being environmentally friendly too. With the cat the boost spikes to 10psi on initial spool then settles to 8psi where is holds until the power falls off past 7k rpm.
For engine management the owner decided on an E6X. We added 1600cc injectors for secondaries and used the stock -SE injectors for primaries. The 1600s are overkill for now but the owner has plans for a full TII/T4 upgrade down the road.
The end results with a minimum of tuning was 247whp and 232lb/ft at a sustained 8psi. So far any of you who are considering turboing an NA engine it can be done, done effectively, and can make good power with a conservative tune.
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