Volvo Penta 7.4 Gi vs GSi rev limiter
 

Just got off the phone with the tech @ the dealer who was telling me both the Volvo Penta 7.4 Gi & GSi has the same rev limiter @ 5100? I know the rpm range of the Gi motor is 4200-4600 & the GSi is 4600 -5000rpms so this doesn't sound right but I don't know. Any one know for sure? I may switch in a 8.2l & use the same intake & ignition so it would be great not needing another ignition module for the higher rpm range.

7.4 Gi 4200 - 4600 rpm - offered both in SX and Duoprop

He is wrong about the 7.4 GSi - 4800 - 5200 rpm and the GSi was only matched up to a Duoprop. Not SX from Volvo OEM stock.

Rev limiter is 100 to 150 rpm's above the MAX rpm range.

Also the 8.2 GSi - 4600 - 5000 RPM's and was only offered in a duoprop as well. OEM Volvo Stock

Volvo codes are as follows

G = general Motors
S = superior output
i = fuel injected engine
L - Limited output if anyone needs to know.

factory OEM Volvo trained for almost 20 years and currently.

just look at the 1999 7.4 GSI cal and the hi rev fuels cut off is set at 5400 and this is with the DPX

You are Correct and the DPX 385 hp / 454 CID and the DPX 415 hp / 502 CID is Volvo High End Series at that timeframe. The DPX outdrive offered some different gear ratios compared to the Duoprop.

standard DP outdrive gear ratio was for the GSI - 454 & 502 was 1. 68:1 and optional 1.78:1

DPX outdrive gear ratio for the 454 / 385 hp and the 502 / 415 hp was 1.47:1 and 1.51:1 and 1.59:1 and 1.68:1 and 1.78:1 and not listing a standard gear ratio. DPX drive / engine package had a tad hotter tune than the DP and SX matched engines.

Also the OP has a 252 Cobalt and I can never ever recall a factory stock 25 footer and down Cobalt with a DPX outdrive.

Thanks

This Cobalt is the 7.4Gi DP with 1.95 F6's. Being @ higher elevation maybe the gears were replaced or came like that from the factory per dealer request? Do you guys know the part number for the GSi or DPX ignition module?

Yes, and they are all the same, right on down to the 4.3. They all use the same module pn 3854003.
The 7.4 & 8.2 (Gi, Gsi, DPX) all share the exact same distributor & ignition system as well.

Correct on the part #.

Your 7.4 Gi did offer these gear ratios. The GSi I already posted. The 7.4 Gi DP gear ratio's were 1.68:1 and 1.78:1 and 1.95:1 as the 1.78:1 was the standard gear ratio for the 7.4 Gi DP offered and the other were optional for the various reasons. Just wanted to make clear that the 1.95:1 was offered for the Gi.

Ok thanks. This Gi motor does have a rev limiter @ 4750rpms. The engine module is #3858570. Is there a different engine module on the GSi?

Yep like I said 100 to 150 rpm over the recommended rpm range for whatever app from Volvo. 454 Gi - 4200 to 4600 rec rpm range.

The 454 - Gi ECM part # currently is 3801320 requiring a harness adaptor as well.

The 454 - GSI ECM part # 3856943 and is out of stock thru Volvo Penta currently. Maybe a dealer or someone still has new on the shelf. Have no idea about that one or just google part #.

If Volvo re enters the ECM to market for the GSi - 454, I bet it will have a new part #.

it's a MEFI 1 with the proper calibration you can set it up for a GI orGSI. They are available and so is the calibration. Your other option as noted is the 2600 or more MEFI 4 conversion.

Ouch, that's a steep conversion. Not sure what I’m going to do with this boat yet but 48GPS is painful. Originally thought of Procharger but Procharger doesn’t offer a kit for the 7.4 VP. Then I was considering a 509 with the VP Gi intake & ignition but the conversion doesn’t seem cost effective. Guess I’ll go back to carbed 509 or just live with the VP Gi?

I've added 496 manifolds & K&N intake filter to this set up & it seems to have lost power? After these mods the boat was in the low 40's GPS. Last weekend I put the stock intake screen back on, 1/4 of fuel, 4 adults the speed is back to 47.5GPS? Does the MEFI need to be reprogramed to take advantage of the better free flowing intake & exhaust manifolds?

if in fact your Cobalt engine is a 1999 and Volvo lists by model number to determine year so with that said if that model number has a WT in it then its a 1999 year model so it should be a a MEFI 3 ecm not a MEFI 1 ecm.

Volvo ECM follows as such MEFI 1 basically up to mid 1998 in which is BY models .

Volvo had no MEFI 2 as they did not even offer it, they went right into MEFI 3 for very late 1998 or very early 1999

Volvo very late 2001 or early 2002 went to MEFI 4
Volvo late 2004 or early 2005 went to E controls no more MEFI controllers for them.

Volvo has used E controls ECM's for the past 10 to 11 years

FYI.

The ECM # is 74LOPFI/99BZ02 & the engine # is the 7.4Gi PWTR. I really don't understand why with better flowing exhaust/ intake & a lake that's 1000' lower in elevation the boat is slower than stock? I think I should be 1 or 2 miles GPS better? It was only two people in the boat when it did 48.5gps but the lake was @ 6000' elevation not 4900' w/ four of us & better exhaust.

Your being limited by your cam, after market exhaust will ad character to the exhaust note and a new intake may improve induction but not matter what you try the cam is holding you back.....maybe the timing curve could be adjusted a bit but not enough to make any real world difference Is this a TBI engine or MPI if its mpi marine intakes are setup differently than automotive they use larger injectors and are sought after by the car community for performance. Thats for the 5.7 as to a 7.4 who know's but why build for a 5.7 and not a 7.4??? lol who knows

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