Expanding HP limit with Ternimator Stealth.

[Kopfjaeger]

Question, I purchased the Terminator Stealth because I wanted to keep the stock look of a carburetor on my BBC 1967 SS 396. The 427 big block I’m building has the capability of easily exceeding the 600 HP limit of the unit. I’m throttling the build a bit to prevent that. In looking over the website, it seems I can increase the injector size to raise the HP limit. Is this as easy as it sounds? Please, I’m all ears. Not that I want 800 HP capability, but I don’t want to get too close to the 600 HP max and run lean at WOT. Please chime in. I’m not tech savvy so please go slow. Joe

[Danny Cabral]

If you're referring to the 205 lb/hr fuel injector upgrade, I think that's only for the regular Terminator TBI. You can upgrade your fuel system if you think it won't keep up.

[Kopfjaeger]

Hmm, that’s unfortunate. I purchased the a Stealth for the reason of keeping a stock look and the better computer. Selling it for a larger and more modern system is not ideal. I also have tight hood clearances with most manifolds so a rail system or a TBI unit I a little taller may not fit with an air cleaner under my hood. I guess I continue to rein in my engine build a little.
Joe

[Danny Cabral]

The 427 big block I’m building has the capability of easily exceeding the 600 HP limit of the unit. I’m throttling the build a bit to prevent that.

Hmm, that’s unfortunate. I purchased the a Stealth for the reason of keeping a stock look and the better computer. Selling it for a larger and more modern system is not ideal.

IF you purchased the wrong EFI system, that's not Holley's fault.

Not that I want 800 HP capability, but I don’t want to get too close to the 600 HP max and run lean at WOT.

You can upgrade your fuel system if you think it won't keep up.

However, I didn't say upgrade the EFI system; I said upgrade the fuel system IF you think it won't support 600 HP. I wouldn't assume you have a problem until a datalog proves it (high Duty Cycle %).

[Kopfjaeger]

Danny, I’m not blaming Holley, that would be stupid to do so. No where in my posts was I blaming Holley, or myself for my choice. I purchased the Stealth because of the above listed reasons and I’m not at all sorry I purchased the Stealth. I still think it was the best choice for my needs. I thought a 600 HP ceiling would be high enough. I’ll just cam the build down, like I intended.

By upgrading the fuel system, I thought you meant the device. I did not buy the Holley install kit. I’m designing the system to provide the Stealth with the amount of fuel it requires (and then some). I’m going to have million questions about ignition components to best work with the Stealth. Thanks for posting on this thread. Joe

[Bdud]

I found this thread a while ago: https://forums.holley.com/showthread...inator-Stealth. Going by this thread you can install the bigger injectors, but you need to change the injector connectors: https://www.efisystempro.com/holley-...pgrade-522-205. I believe you can increase the fuel pressure to a max of 75 psi, so you might be able to match the Stealth to your engine output with the stock injectors.

[92GTA]

I reached out to Holley as I'm in the same boat with my Terminator Stealth. This is the response that I received:
Thanks for contacting Holley Technical Support! The following advice WILL void any warranty you have as this is advanced custom work. If you're comfortable with that, proceed, otherwise you will need to go a different direction with a different throttle body setup.

The Terminator Stealth has a different harness internally than the Terminator. You can use an injector package like 522-205 but you'd need to change the injector connectors to the style like used on 558-439. It's a Sumitomo MT injector connector: https://www.automotiveconnectors.com...connector.html. I cannot guarantee fitment of any other injector inside that chassis as it's a unique spacer to work out of inside the faux fuel bowls.

Another option. Those 80 lb/hr injectors are rated at 43.5 PSI. You can push them to 60 PSI and not suffer any consequences and gain some flow. 320 lb/hr total would turn into 378 lb/hr. That could get close to 675-700 HP depending on what the engine likes. You'd have to see what duty cycle the injectors hit on a pull to see if you need that fuel, but that's my theoretical max power at 90% duty cycle. I wouldn't want to drive the injectors harder than that, so you have some margin of safety.

If you have any other questions or would like a custom quote please feel free to reply to me or if you need immediate help, please feel free to call me on the Tech Line at 1-866-464-6553
-Ethan @ Holley Tech

The engine I'm building is looking at be about 700 HP, so I'm going to up the FP and see what duty cycle I'm at when tuning on the chassis dyno. If my engine absolutely needs more, then I plan on doing the injector upgrade.

[Bill C]

Are you using a single-plane intake? If so, you could always add injector bungs, the correct injector for your application, and simply use the Terminator Stealth as an air only throttle body, you would just configure it as a custom setup. If you do the rails & bungs right, you still have a stealth look. Plus it gives you the benefit of sequential control of injectors, and individual cylinder timing control if you went to Coil-Near-Plug.

Or you could simply sell the Terminator throttle body and go with one of the MPFI big block intakes that Holley, Mercury Marine, and others offer. Old school is cool, but do not be afraid to embrace a fully modern SEFI setup. It'll drive better, probably last longer, and usually make a little more top end power to boot.

[Vortechys]

A little late, but you can use the 205 lb/hr injectors in the Stealth TB. You need to change the connector ends of injector harness to be compatible with the new injectors. I've run my 427 FE Ford with this setup and it works great as long, as you modify the Injector Off Time and injector size (Fuel Injector Information) in the Holley EFI software.

[Kopfjaeger]

Thanks for the additional info! My engine is completed and has an appointment at the dyno, so I should soon know where my fuel system stands. I should be slightly below the 600 HP ceiling, but it’s good to know I can pick up a bit of headroom by increasing pressure to the throttle body. Joe

[Kopfjaeger]

Dyno results are in. 534 HP @ 5900 and 534 lb/ft of torque! Very flat curves. My Terminator Stealth will do just fine out of the box! Joe

[Danny Cabral]

Thanks for a good update!